Tripoli, Libya — Each side of the conflict in Libya pushed forward on Saturday as militia forces loyal to Col. Muammar el-Qaddafi launched a second day of attacks on the rebel-held city of Zawiyah, just 30 miles west of the capital, and a ragtag rebel army moving from the east won its first ground battle to take the oil port of Ras Lanuf, about midway down the Mediterranean coast.

Both sides were girding for a confrontation in the coming days at the port of Surt, the town where Colonel Qaddafi was born and which blocks the rebels’ progress toward the capital, Tripoli, where extremely heavy gunfire could be heard in the center of the city before dawn Sunday.

Eighteen days after it began with spirited demonstrations in the eastern city of Benghazi, the Libyan uprising has veered sharply from the pattern of relatively quick and nonviolent upheavals that ousted the leaders of Tunisia and Egypt. Instead, the rebellion here has become mired in a drawn-out ground campaign between two relatively unprofessional and loosely organized forces — the Libyan Army and the rebels — that is exacting high civilian casualties and appears likely to drag on for some time.

That bloody standoff was evident on Saturday in Zawiyah, the northwestern city seized by rebels a week ago, where the government’s attacks raised puzzling questions about its strategy. For the second day in a row its forces punched into the city, then pulled back to maintain a siege from the perimeter. Hours later, they advanced and retreated again.

By the end of the day, both sides claimed control of the city.

Foreign journalists were unable to cross military checkpoints to evaluate reports of what Zawiyah residents called “a massacre.”

Witnesses there began frantic calls to journalists in Tripoli at 6 a.m. Saturday to report that soldiers of the Khamis brigade, which is named for the Qaddafi son who commands it and is considered the family’s most formidable force, had broken through the east and west gates of the city. “They are killing us,” one resident said. “They are firing on us.”

The militia attacked with tanks, heavy artillery and machine guns, witnesses said, and the explosions were clearly audible in the background. “I am watching neighbors dying unarmed in front of their homes,” one resident said. “I don’t know how many are being killed, but I know my neighborhood is being killed.”

In a telephone interview a little more than three hours after the attack began, another resident said: “Everything is burning. We don’t know from which side they are shooting us, from the buildings or from the streets. People are falling everywhere.”

The rebels, including former members of the Libyan military, returned fire. Although a death toll was impossible to determine, one resident said four of his neighbors were killed, including one who was found stripped of his clothes.

A correspondent for Sky News, a British satellite TV channel and the only foreign news organization in the city, reported seeing the militia fire on ambulances trying to remove the wounded from the streets. The reporter also said she had seen at least eight dead soldiers and five armored vehicles burning in the central square.

At 10 a.m., witnesses said, the Qaddafi forces abruptly withdrew, taking up positions in a close circle around the city.

Some rebels painted the pullout as a victory. A spokesman for the rebels told Reuters they had captured three armored personnel carriers, two tanks and a pickup truck.

But other rebel supporters acknowledged that there was little evidence that they had inflicted enough damage on the militia to force the retreat. Residents said they were unable to leave and visitors, including journalists, could not enter. “If you come here you will not believe what you see,” one resident implored. “It is like a war zone.”

Around 4 p.m., the militia attacked again. A witness said as many as six tanks rolled through town, there were more skirmishes with the rebels, and then the tanks left as quickly as they had arrived.

“We don’t know which side they are coming from,” one witness said in a panicked phone call.

At a news conference Saturday night in Tripoli, Deputy Foreign Minister Khalid Kaim described Zawiyah as “peaceful for the moment.” Another foreign ministry official, Yousef Shakir, called it “99 percent” under government control.

Officials also showed videos that they said proved their opponents were not peaceful demonstrators. Aerial video of Zawiyah showed tanks on the streets and antiaircraft guns on the roofs of mosques.

Another video was said to show rebel interrogations and executions, which the officials likened to the tactics of Al Qaeda.

Despite all the footage of rebel weapons, the officials denied they were fighting a civil war. “There are some people who are acting in contravention of the law, which can happen anywhere,” a spokesman said. Mr. Shakir said: “It is a conspiracy, a very highly organized conspiracy. We will show the foreign hands in the near future.”

In Benghazi, the rebels’ de facto capital, the rebels took further steps toward political organization. Their shadow government, the Libyan National Council, held its inaugural meeting and appointed a three-member crisis committee.

Omar Hariri, who participated in Colonel Qaddafi’s 1969 coup but was later jailed, was appointed transitional defense minister. Ali Essawi, a former ambassador to India, was appointed foreign minister.

Abdul Hafidh Ghoga, a spokesman for the council, seemed to back away from previous calls by rebel leaders for Western airstrikes, saying emphatically, “No troops on Libyan soil.” But he added that the rebels would welcome the imposition of a no-flight zone, and said, “We require help to stop the flow of mercenaries into this country.”

While the rebels may have a new defense minister in Benghazi, their fighters on the eastern front did not appear to be taking orders from anyone as they pushed past Ras Lanuf, an oil refinery town that they retook from Colonel Qaddafi’s loyalists on Friday night.

Armed with rocket-propelled grenade launchers, the rebels advanced confidently by car and foot through the desert until a fighter jet was heard. Even a rumor of a jet engine in the distance would send the fighters in a mad dash through the dunes, searching for cover and firing in the air.

A rebel convoy that encountered an army checkpoint on the road to Surt made a quick U-turn and sped away.

There did not appear to be much of an air war, although the sounds of fighter jets were heard throughout the day. The convoy was strafed by a helicopter, although no casualties were reported.

In Ras Lanuf, the bodies of two pilots were found in the wreckage of a Libyan fighter jet, witnesses said. A rebel claim that the jet had been shot down could not be confirmed.

Rebel military leaders said the explosions at a large ammunition dump on Friday in Benghazi were caused by an airstrike. The explosions leveled at least three buildings, toppled power lines more than 300 yards away and killed at least 16 people.

There were conflicting reports on casualties in the previous day’s battle for Ras Lanuf. A rebel said that 12 rebels were killed, while hospital officials in the nearby city of Ajdabiya said 5 rebels had been killed and 31 were wounded, The Associated Press reported. Reuters cited doctors saying 26 had died.

* David D. Kirkpatrick reported from Tripoli, and Kareem Fahim from Benghazi, Libya. Ed Ou contributed reporting from Benghazi, and Tyler Hicks from Bin Jawwad, Libya.

Opposition in Libya Struggles to Form a United Front

The calls for foreign aid have amplified divisions over intervention

Rebel leaders in Darnah warned that they would oppose any
foreign interference with arms

Benghazi, Libya — In less than three weeks, an inchoate opposition in Libya, one of the world’s most isolated countries, has cobbled together the semblance of a transitional government, fielded a ragtag rebel army and portrayed itself to the West and Libyans as an alternative to Col. Muammar el-Qaddafi’s four decades of freakish rule.

But events this week have tested the viability of an opposition that has yet to coalesce, even as it solicits help from abroad to topple Colonel Qaddafi.

Rebels were dealt military setbacks in Zawiyah and Ras Lanuf on Tuesday, part of a strengthening government counteroffensive.

Meanwhile, the opposition council’s leaders contradicted one another publicly. The opposition’s calls for foreign aid have amplified divisions over intervention. And provisional leaders warn that a humanitarian crisis may loom as people’s needs overwhelm fledgling local governments.

“I am Libya,” Colonel Qaddafi boasted after the uprising erupted. It was standard fare for one of the world’s most outrageous leaders — megalomania so pronounced that it sounded like parody. It underlined, though, the greatest and perhaps fatal obstacle facing the rebels here — forging a substitute to Colonel Qaddafi in a state that he embodied.

“We’ve found ourselves in a vacuum,” Mustafa Gheriani, an acting spokesman for the provisional leadership, said Tuesday in Benghazi, the rebel capital. “Instead of worrying about establishing a transitional government, all we worry about are the needs — security, what people require, where the uprising is going. Things are moving too fast.”

“This is all that’s left,” he said, lifting his cellphone, “and we can only receive calls.”

The question of the opposition’s capabilities is likely to prove decisive to the fate of the rebellion, which appears outmatched by government forces and troubled by tribal divisions that the government, reverting to form, has sought to exploit. Rebel forces are fired more by enthusiasm than experience. The political leadership has virtually begged the international community to recognize it, but it has yet to marshal opposition forces abroad or impose its authority in regions it nominally controls.

Organizers acknowledge the chaos but contend that there is no one else to talk to.

“We require support, whether it’s military or otherwise, we require help,” Abdel-Hafidh Ghoga, the deputy leader of the provisional leadership, told a news conference in Benghazi. “The international community has to assume its duty at this point.”

While the mood remains ebullient in parts of eastern Libya, largely because few believe that Colonel Qaddafi can reconquer a region that long seethed under his rule, it is more sullen in Benghazi, a Mediterranean port and Libya’s second largest city.

At the courthouse that has served as a government headquarters, bedlam reigned Tuesday, as gusts of wind slammed doors shut and shattered a window. Nationalist music blared over hurried conversations that unfolded beneath cartoons lampooning Colonel Qaddafi.

Security has begun to deteriorate, with gunfire echoing in the distance, some robberies and assailants’ throwing a grenade at a hotel housing foreign journalists.

At the front, three and a half hours away, rebels sought to recover from a government offensive that forced them from Bin Jawwad and sent them reeling toward Ras Lanuf, a strategic refinery town. The government also appeared to deal setbacks to the rebels in Zawiyah, a rebel-held town near Tripoli, and Misratah, a strategic coastal city.

With momentum seeming to shift, the rebels face the prospect of being outgunned and outnumbered in what increasingly looks like a mismatched civil war.

“They don’t understand,” said Sami Tujan, an officer trying, unsuccessfully, to command rebels near a checkpoint. “They’re a big target.”

The rebels won their initial battles with an assortment of aging but effective weapons, and a seemingly plentiful supply of ammunition, including some from North Korea and Russia. On the beds of Toyota pickup trucks, many of the soldiers mounted an old Soviet heavy machine gun, which they referred to by the 14.5-millimeter rounds it fires. The guns are bundled together and used as antiaircraft weapons, and may have been responsible for downing a government warplane earlier this week near Ras Lanuf. Men holding rocket-propelled grenade launchers complete the patchwork rebel air-defense system.

At the front lines at Ras Lanuf, the opposition forces relied on more rudimentary tracking methods to spot planes: a lanky man standing on top of a large dump truck with a pair of binoculars, along with hundreds of sets of ears of eager volunteers.

Even then, the government’s Soviet-made planes mostly operated with impunity. Government forces have also marshaled artillery, better tanks and helicopters that the rebels cannot match.

On Tuesday, as government forces gathered near Ras Lanuf, rebels strategized and argued among themselves, complaining that they did not have enough rocket-propelled grenades and that a spy was among them.

Logistics, namely resupplying the front, has proved to be a challenge for the rebels. So has leadership. Small units of men who said they belonged to specialized branches of Libya’s army joined the fight, including members of special forces units and paratroopers. Some senior officers are also seen at the front, but many of the rebels are bankers, policemen and the unemployed, who have formed enthusiastic but somewhat hapless brigades.

“Apart from a few mechanized units in Benghazi and Tobruk, and a few armored battalions near Bayda, rebel-controlled areas lack any substantial hardware with which to take on the pro-Qaddafi stronghold of Tripoli,” said a report on Tuesday by the London-based International Institute for Strategic Studies. “The pro-Qaddafi regions are also well garrisoned with artillery, antiaircraft and mechanized formations,” it added.

After government authority collapsed in much of eastern Libya, residents set up what they call local councils of varying numbers of representatives — three in Darnah, six in Bayda. Theoretically, each is supposed to send a representative to Benghazi, where the opposition has set up a group called the Provisional Transitional National Council of Libya, a kind of state in waiting. Composed of 30 representatives, it is led by Mustafa Abdel-Jalil, a former justice minister and perhaps the sole figure who enjoys national support.

Its authority remains tentative, a point acknowledged by those involved. “We didn’t have any authority, of course; we just gave ourselves authority,” said Iman Bugaighis, a spokeswoman for the council. “Nobody has any political experience.”

The council has barely begun to address the major choices the rebels need to make: whether to support foreign intervention and whether to negotiate in any way with the government.

The council has pleaded for a no-flight zone, still being debated by the West, but rebel leaders in Darnah warned that they would oppose any foreign interference with arms.

In his news conference, Mr. Ghoga ruled out any talks with the government, though Mr. Abdel-Jalil, theoretically his superior, told an Arabic satellite channel that if Colonel Qaddafi left in 72 hours, no one would pursue him.

“How do we talk about something that hasn’t been proposed?” Mr. Ghoga asked.

Opposition leaders also differ on whether to formally declare a transitional government, underlining fears that it may lay the groundwork for Libya’s partition. Two of its representatives met European officials on Tuesday, but the council has yet to unite with disparate, divided opposition groups abroad, activists say.

“There is no communication between opposition groups and no leadership for the opposition,” said Adem Arqiq, an exiled Muslim Brotherhood member in Dublin. “There are opposition groups in Europe, in the United States and in some Arab countries, but each works for himself. There were efforts to unify them, but they failed.”

For days, convoys of aid, many from Islamic relief organizations, have barreled across the Egyptian border, helping stanch shortages, in a remarkable show of organization and solidarity. Mr. Gheriani estimated that Benghazi had six months of supplies, and the United Nations was sending more aid to the port.

But in the hinterland, where local councils are still struggling to reconstitute bureaucracies that collapsed last month, some worry a crisis is approaching.

“No one knows how long supplies will last — a week, two weeks,” said Ahmed Boughrara, an engineer and organizer in Bayda. “Then it’s going to be a huge crisis.”

Some have expressed a more lurking concern: that in a protracted fight, it may grow difficult to maintain the unity that the opposition has sought to bridge religious and tribal divides.

“The longer this conflict lasts, the more people are going to be radicalized,” said Ibrahim el-Gadi, a hydrogeologist in Darnah, whose son was wounded in a fight with government forces. “We are not now, but it will be so if this conflict doesn’t finish.”

* David D. Kirkpatrick contributed reporting from Tripoli, Libya, and Nada Bakri from Beirut, Lebanon.