National Transitional Council (NTC) chief Mustafa Abdel Jalil, meanwhile, promised the elusive Kadhafi and his senior aides they would be given a fair trial in Libya if they surrendered.
Speaking in the eastern city of Benghazi, where the rebellion began in February, Jalil also called for emergency humanitarian aid for the capital, stressing the lack of medical supplies.
"We are calling all the humanitarian organisations and telling them that Tripoli needs medicines, first aid products and surgical material," he told a news conference.
Blaming "sabotage by Kadhafi's forces" for shortages of water and electricity in Tripoli, he said, "We are working on resolving these problems."
While fighting was still under way on various fronts, focus was increasingly turning to a post-Kadhafi era, with calls for reconciliation and a peaceful transition.
NTC spokesman Mahmud Shammam said in the capital the rebels would start distributing 30,000 tons of petrol to Tripoli residents immediately, and would be providing cooking gas within the next 48 hours.
They were also working to restore the Zawiyah refinery, Shammam said, pleading for patience and calling on all public, private and oil sector employees to return to work.
"We are starting from point zero in this situation. Do not ask for miracles, but we promise to try to make this difficult period as short as we can," Shammam said.
He admitted there was still resistance left.
"Anybody who thinks that there is not a fraction of people who support Kadhafi or that there is no fifth column who will try to trouble the peace of Tripoli would be mistaken."
Electricity in the capital is out for several hours a day. Many districts have no water and the price of food and petrol has skyrocketed, while mountains of rubbish have piled up on the sweltering streets.
Even so, life bore a semblance of normality in central Tripoli on Saturday, with some shops open and people out and about preparing for the end of the Muslim fasting month of Ramadan.
Tripoli airport, held by the rebels, was still being targeted by sporadic shooting and shelling but the insurgents said they had expanded the area under their control.
The dawn assault on the 32 Brigade base just south of the capital left 11 rebels dead and "higher casualties on the other side," according to a rebel commander.
The complex of mustard-walled buildings had its walls holed by bombs, its roofs caved in and windows blasted open.
Within hours of the end of the battle, rebel fighters had completely emptied the magazines of weapons from Belgium, Germany, Italy, South Korea, Russia and the United States, an AFP correspondent at the scene said.
In an adjoining cinder-block building lay the blackened bones of at least 50 people. A former captive who had been transferred because it was overcrowded said Kadhafi loyalists had thrown in hand grenades and fled.
The rebels late Friday captured the Ras Jdir border post on the frontier with Tunisia, through which it was feared Kadhafi, his henchmen and family might escape.
They also took two of the villages from where Kadhafi forces had been bombarding Zuwarah, between the border and the capital, an AFP correspondent accompanying them said.
Meanwhile the Algerian foreign ministry denied as "baseless" an Egyptian news agency report that six armoured Mercedes that could have been carrying Libyan officials, even Kadhafi, had crossed into Algeria late Friday.
The rebels, who are making slow progress in their advance on Kadhafi's hometown of Sirte, east of Tripoli, another possible bolthole, want to find him so they can proclaim final victory in the six-month-old uprising.
"We call on Moamer Kadhafi and his associates to surrender so we can protect them and spare them illegal execution," Jalil said. "We guarantee them a fair trial, whatever their position."
The rebels have offered a $1.7 million dollar reward for Kadhafi's capture, dead or alive.
The United Nations, African Union, Arab League and European Union urged both sides in Libya to avoid reprisals, EU foreign policy chief Catherine Ashton said after talks of the so-called Cairo Group.
"Colonel Kadhafi must avoid further bloodshed by relinquishing power and calling on those forces that continue to fight to lay down their arms and protect civilians," she said.
She added: "Today, under UN leadership, we agreed to call on all parties to respect international humanitarian and international human rights obligations. There should be no reprisals."
Ashton said the Cairo Group, which also includes the Organisation of Islamic Cooperation, "emphasised that the transition in Libya should be Libyan-led and inclusive."
UN chief Ban Ki-moon said after the talks, which he chaired, that an international police force may need to be sent to Libya, which is "awash" with small arms.
NTC number two Mahmud Jibril took over Libya's seat on the Arab League at a ministerial meeting in Cairo late Saturday, where the rebel flag replaced Kadhafi's green standard.
Libya had been suspended in February after Kadhafi ordered a bloody crackdown on protesters.
Arab League chief Nabil al-Arabi said experience had proved "the security option and recourse to force are pointless against revolutions and uprisings demanding radical change when these demands are legitimate."