There was no sign of a swift end to the war, which they have said will only end when Gaddafi is captured dead or alive, but the rebels claimed victory in Ras Jdir, raising their flag at the border post with Tunisia after clashes with loyalists.
A rebel detachment was also turning its attention to Sirte, Gaddafi's birthplace 450 km (300 miles) east of Tripoli, where British aircraft have fired cruise missiles at a headquarters bunker.
A city beyond rebel control on the Mediterranean coast, some believe Gaddafi might seek refuge there among his tribesmen. Loyalist forces also still hold positions deep in the Sahara desert, days after gleeful rebels took much of the capital, ransacked Gaddafi's compound and paraded their stolen souvenirs.
"Sirte remains an operating base from which pro-Gaddafi troops project hostile forces against Misrata and Tripoli," a NATO official said, adding that its forces had also acted to stop a column of 29 vehicles heading west toward Misrata.
Leaders of the National Transitional Council, which has Western support, pressed foreign governments to release Libyan funds frozen abroad, warning of its urgent need to impose order and provide services to a population traumatised by six months of conflict and 42 years of eccentric, personal rule.
But Gaddafi's long-time allies in Africa, beneficiaries of his oil-fueled largesse and sympathisers with a foreign policy he called anti-colonial, offered him a grain of comfort and irked the rebels by refusing to follow Arab and Western powers in recognising the NTC as the legal government.
Combined with the reluctance of major powers like China, Russia and Brazil, to see Europeans and Americans dominate a nation with Africa's biggest oil reserves, the African Union's resistance may slow the pace at which funds are released.
Mahmoud Jibril, head of the government in waiting, said time was short. Visiting Turkey, he said: "We have to establish an army, strong police force to be able meet the needs of the people and we need capital and we need the assets."
While many African states have recognised the NTC, the AU would not do so as long as fighting continued, South African President Jacob Zuma, a vocal advocate for Gaddafi, said after a meeting in Addis Ababa at which the AU called for all sides in the conflict to negotiate peace and work for democracy.
If fighting continues unchecked, there are fears that Libya's conflict will spill over into the remote regions of Mali, Niger, Chad and Mauritania.
Algeria has said it believes the chaos inside Libya, and large quantities of weapons circulating there, are already being exploited by al Qaeda's North African branch.
And an influential former Malian rebel, believed to have been involved in the trade of looted weapons from Libya, has been killed in Mali, officials said on Friday.
However, taking control of the Ras Jdir border post reopens a path for humanitarian aid and other supplies from Tunisia to Tripoli, where stocks of medicines and fuel are running low.
"The revolutionaries control the area, but there are no services, water or electricity," said Abdul Qader, fleeing Abu Salim in the capital, just one area where bodies still lay in the streets from recent battles or apparent revenge killings.
Rebel leaders are determined to show they are in charge, though estimates vary of when the NTC will move formally from its Benghazi base in the east to the war zone that is Tripoli.
"We have come to operate the country. We are now the legal authority," declared Mohammed al-Alagi, a lawyer who has been the NTC's justice minister for some months, as he met foreign journalists in the capital wearing a rebel flag as a bandana.
NTC leaders stress they want to work with other rebel groups that sprang up later in the west as well with those who have previously supported Gaddafi.
Driving home the unity message, rebel fighters in Tripoli, who come from all over a country fragmented by tribal and regional divisions, have been placed under the unified command of a military council, Tripoli's top rebel commander said.
GADDAFI "UNDER SIEGE"
Alagi voiced confidence that Gaddafi and his entourage of sons and aides was surrounded and would soon be captured: "The area where he is now is under siege," he told Reuters, while declining to say where in Tripoli he thought Gaddafi was. "The rebels are monitoring the area and they are dealing with it."
Such confidence has proved misplaced since the irregular armies overran Gaddafi's compound on Tuesday, however, and analysts do not rule out that the 69-year-old, a veteran master of surprise, might have slipped away to rally supporters for an insurgency. He has not been seen in public for two months, but made a defiant audio broadcast on Thursday.
A convoy of six Mercedes cars crossed from Libya into Algeria on Friday, Egypt's state MENA news agency reported, quoting a rebel source. It was impossible to verify the report, but MENA quoted the source as speculating that senior Libyan officials or Gaddafi himself and his sons may have fled Libya.
NATO forces, notably from France and Britain, are helping the rebels. Many analysts assume they are giving intelligence and may have their own special forces troops on the ground.
In Benghazi, rebel military spokesman Ahmed Bani said the bombing in Sirte was aimed at ammunition stores and depots for Scud missiles. He said there had also been fighting around Bin Jawad, which lies on the way to Sirte.
"After this bombing, maybe the people there will try to rise up," he said, saying NTC commanders were also in contact with tribal chiefs in Sirte, hoping to avoid bloodshed.
Such negotiations will be as big a challenge as security for Libya's new rulers as they try to meet expectations of young men now bearing arms and to heal ethnic, tribal and other divisions that have been exacerbated by civil war.
Despite sporadic gunfire as rebel fighters tried to take pockets of loyalist resistance, Tripoli was quieter than in recent days.
Dead bodies, the stench of rotting garbage in the oppressive summer heat, wrecked cars and the other detritus of war were evidence of frantic battles and wildly erratic firing.
Yet some of Tripoli's 2 million people ventured out to local mosques, some praying Gaddafi could be found by Monday, when Muslims mark the end of the fasting month of Ramadan with the festival of Eid.
"Gaddafi is the biggest criminal and dictator and we hope we will find him before the end of Ramadan," said Milad Abu Aisha, a 60-year-old who joined friends at his local mosque for traditional worship on the last Friday of Ramadan.
"It will be the happiest Eid in 42 years," said Mohammed al-Misrati, a 52-year-old office worker who was among hundreds streaming toward the mosque under the protection of armed local men who have formed ad hoc security units across the capital.
"We have a taste of freedom after 42 years of repression."