The UN is set to unfreeze $1.5bn (£1bn) in frozen Libyan assets to help with immediate humanitarian needs.
In an audio message, Col Gaddafi has called on Libyans to "fight and destroy" the rebels.
The message was broadcast by a pro-regime TV station and addressed to the people of Sirte, which is the rebels' next target. It was unclear when it was recorded.
"Libya is for the Libyan people and not for the agents, not for imperialism, not for France, not for Sarkozy, not for Italy," said Col Gaddafi. "Tripoli is for you, not for those who rely on Nato".
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Col Gaddafi: "Do not leave Tripoli to the rats, fight them, defeat them as soon as possible"
He urged the youth of Tripoli to fight "street by street, alleyway by alleyway, house by house" and said women too could fight "from inside their homes".
The rebels have announced an amnesty for anyone within his "inner circle" who captures or kills him and a $1.7m (£1m) reward for his capture "dead or alive".
The rebel National Transitional Council (NTC) also said they had now moved their political base to the capital from their stronghold of Benghazi.
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Thanks to the rebels, Gaddafi has been thrown into the dustbin of history”
End Quote Habib Lamine Freed Libyan prisoner
South Africa had been blocking the UN motion to release $1.5bn in Libyan assets frozen under sanctions - which was proposed by the US - amid concerns that giving money to the NTC implied it was being formally recognised as Libya's leader, something South Africa and the African Union have not done.
The BBC's Barbara Plett at the the UN says the US agreed to remove specific references to the NTC, enabling the motion to pass.
Mahmoud Jibril, the head of the NTC, earlier said Libya needed "urgent help" to pay salaries and enable reconstruction, to ensure the stability of Libya in the immediate future.
Italy has already promised to release more than 350m euros of Libyan assets frozen in Italian banks.
In other developments:
- The Arab League has given full backing to the National Transitional Council (NTC) as the legitimate representative of the Libyan people
- The International Monetary Fund has said it will recognise the NTC as Libya's leaders when there is "a clear, broad-based, international recognition"
- UK Defence Minister Liam Fox has confirmed that Nato is providing intelligence and reconnaissance assistance to rebels hunting Col Gaddafi
- A ship that can carry 200 people has left Tripoli for Benghazi, carrying some of the foreign nationals in Libya
Handcuffed bodies
Thursday saw gunfights erupting in the Abu Salim district of Tripoli, close to a notorious prison and one of the few remaining Gaddafi holdouts in the city.
There were further battles near the Corinthia Hotel about 1.5km (a mile) from Martyrs Square - formerly Green Square - where most foreign journalists are based.
Sporadic gunfire was also heard at Col Gaddafi's Bab al-Aziziya compound - the area is now under the control of the rebels, who have broken into the complex tunnel system below.
The BBC's Rupert Wingfield-Hayes visited a hospital in the Mitiga district of Tripoli which had received the bodies of 17 rebel fighters.
One survivor said the group had been held at a makeshift prison in Tripoli where they were tortured and then sprayed with bullets as the Gaddafi forces retreated.
Dr Hoez Zaitan, a British medic working at the hospital, said about half the bodies had bullet wounds to the back of the head while others had disfiguring injuries to their limbs and hands.
He said the bodies had been examined for possible evidence to be used at a war crimes tribunal.
The Red Cross is urging all sides to respect the rules of war Meanwhile, the bodies of at least a dozen pro-Gaddafi fighters have been found on a roundabout in the centre of Tripoli, two of whom had their hands tied behind their backs.
There were reports that one body had an intravenous drip in the arm and that others were badly burned.
Amnesty International says it has "powerful testimonies" of abuses by both sides in Zawiya, including allegations of violence by rebels African migrant workers accused of being mercenaries.
The UN has said it is looking into reports of summary killings and abuses by both sides and urged "all those in positions of authority in Libya... to take active steps to ensure that no crimes, or acts of revenge, are committed".
The Red Cross says each side is believed to have hundreds of prisoners and has urged all parties to respect the rules of warfare.
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