Moammar Kadafi\'s whereabouts remain a mystery, but his tanks and snipers take positions in areas of the capital. Rebels report heavy casualties, and NATO indicates that airstrikes will continue.

Libyan rebel fighters celebrate as they drive through a district in Tripoli, the capital. (Bob Strong, Reuters / August 22, 2011)

Rebels pouring in from the countryside strengthened their grip on the Libyan capital, setting up checkpoints and securing buildings even as longtime leader Moammar Kadafi evaded their grasp and pockets of his loyalists continued to put up fierce resistance.

Heavy fighting rumbled Monday around Kadafi\'s Bab Azizia compound in southern Tripoli, and throughout the capital rebels said they had sustained heavy losses. The opposition forces claimed control of about 80% of the city, which was at once jubilant with waving flags and precarious with the rattle of gunfire.

Attention quickly focused on how the Transitional National Council, the rebels\' governing body, would impose order on a fractious tribal nation battered by six months of revolt. The rebels are prone to divisions and Western officials worry that power struggles and the desire for revenge may threaten stability much as they did after the fall of Saddam Hussein in Iraq.

Photos: The Libyan rebellion

Kadafi\'s tanks and snipers took strategic positions in several Tripoli neighborhoods, but it was uncertain if the mercurial man who referred to himself as Brother Leader and ruled the nation for nearly 42 years could muster a potent counterattack.

NATO indicated that it would continue its airstrikes against the Libyan leader\'s army. That poses a high risk of civilian casualties in Tripoli, a dense urban landscape with more than 1.6 million people. But the pressing question for rebel leaders and NATO commanders was Kadafi\'s whereabouts. Unlike on previous days, the Libyan leader released no new audio broadcasts.

"We do not know if he is inside or outside Libya," Mustafa Abdul Jalil, the head of the rebel government, said during a news conference in the eastern city of Benghazi, the insurgents\' de facto capital.

Underscoring the importance of that question in a country emblazoned with Kadafi\'s image and shaped by his personality, one Tripoli resident said: "We cannot feel peace. We cannot feel victory until we see Kadafi captured."

East of Tripoli, rebels said Kadafi\'s forces were retreating from Port Brega on the coastal highway toward Surt, Kadafi\'s birthplace and tribal stronghold. Kadafi\'s forces reportedly fired a Scud missile from near Surt on Monday; the target was unclear.

The rebels received support from governments around the world, including Egypt, which is struggling to build a democracy after its revolution overthrew President Hosni Mubarak in February. The United Nations said it was organizing a meeting with the Arab League and African Union to help Libya emerge from Kadafi\'s legacy.

"Now is the time for all Libyans to focus on national unity and reconciliation," Ban Ki-moon, secretary-general of the U.N., told journalists. "This is a hopeful moment but also there are risks ahead."

Italian Foreign Minister Franco Frattini said officials of Italy\'s oil giant, Eni, had arrived in Libya to try to determine when it could restart its oil facilities. Before the uprising, Libya exported about 1.6 million barrels of oil a day, amassing about $50 billion a year in revenues for a population of only 6 million. But much of the money never reached Kadafi\'s fellow Libyans, who clamored for schools, hospitals and other institutions.

Prime Minister David Cameron of Britain, one of the main participants in the North Atlantic Treaty Organization campaign against Kadafi, told reporters in London that "his regime is falling apart and is in full retreat."

The latest information is "that the vast majority of Tripoli is now being controlled by free Libyan forces, although fighting continues and some of it is extremely fierce," he said.

Rebels in pickup trucks laden with high-caliber guns roared into Tripoli throughout Monday. Insurgent leaders set up checkpoints and secured buildings. Representatives of the Transitional National Council met with Kadafi loyalists to prevent chaos from sweeping the capital. The effort was part of a larger aim to create unity among disparate tribes and ethnicities whose differences Kadafi had manipulated for decades.

It remains to be seen, though, whether Berbers in the west, whose rebel forces reached the capital first, will cooperate with tribes from the east. Both sides were united in defeating a dictator, but those bonds will be tested in debates over the distribution of Libya\'s oil wealth and a new national government.

"The challenge for Libyans will be to agree on transitional leaders, but this won\'t be easy given all the sects and tribes," said Ammar Ali Hassan, an analyst in Cairo. "The problem will be reaching a consensus."

Internal divisions widened among insurgents in recent months. They led to the assassination in July of Gen. Abdul Fatah Younis, the rebels\' military commander and former head of security for Kadafi. U.S. and European officials have been meeting with rebel leaders in Benghazi in an attempt to instill democratic principles and avoid recrimination in the country, which is awash in guns.

"The question is: Who is getting all those weapons the rebels are seizing in the many stockpiles in Tripoli?" said Michael Corgan, a professor of international relations at Boston University. "How are those weapons going to be used? Who will keep order once the forces loyal to Kadafi and his mercenaries are neutralized? If all the Kadafi apparatus of state power is dismantled, who rules?"

The rebel leader Jalil, who was Kadafi\'s justice minister before he joined the revolution, said, "I call on all Libyans to exercise self-restraint and to respect the property and lives of others and not to resort to taking the law into their own hands."

No transition is "ever smooth or easy," Britain\'s Cameron said. "Our task now is to do all we can to support the will of the Libyan people, which is for an effective transition to a free, democratic and inclusive Libya. This will be and must be and should be Libyan-led and a Libyan-owned process with broad international support."

The Kadafi government said that 1,300 people had been killed and more than 3,000 injured since Saturday. Those figures could not be independently confirmed. Reuters cited a Libyan government official as saying that 376 people on both sides had been killed, and about 1,000 wounded.

Rebels said they arrested a third son of Kadafi\'s, Saadi, who commanded an army unit. The International Criminal Court was negotiating with rebel leaders over the fate of another Kadafi son, Seif Islam, the onetime heir apparent, who was captured Sunday and faces charges of crimes against humanity. The ICC wants him transferred to its headquarters in The Hague.

Al Jazeera reported that one of the sons in custody, Mohammed, had escaped. It also quoted unidentified sources as saying the body of a fourth son, Khamis, who was in charge of the elite 32nd Brigade, may have been recovered along with that of Abdullah Sanoussi, Kadafi\'s intelligence chief. The reports could not be independently confirmed.

The damage to Kadafi\'s power structure has been devastating, but Libyans still may find it difficult to disentangle themselves from his legacy.

"The thing about Kadafi," said Hassan, "was that he was the regime and the regime was him."