It will be Libyans who will build their new nation, says Barack Obama
The African Union (AU) has recognised Libya's interim leaders the National Transitional Council (NTC) as the country's de facto government.
It came as US President Barack Obama said after meeting NTC chairman Mustafa Abdul Jalil that his ambassador was to re-open an embassy in Tripoli.
Meanwhile, Col Muammar Gaddafi warned opponents Nato support would not last.
And a revolutionary commander has suggested the deposed leader's forces are still recruiting mercenaries.
The AU, a pan-African body which has frequently been criticised for its lack of speed when reacting to events in neighbouring states, said that it was ready to help the NTC in its efforts to build an inclusive government.
"The African Union stands ready to support the Libyan people as they rebuild their country towards a united, democratic, peaceful and prosperous Libya," said the president of Equatorial Guinea, Teodoro Obiang Nguema, who holds the bloc's rotating chair.
He made the announcement after consulting with the panel in New York ahead of the UN General Assembly.
After meeting Mr Obama in New York, interim government leader Mustafa Abdul Jalil thanked the UN and the international community for its involvement in Libya but warned that their task had only just begun.
New Libyan leader Mustafa Abdul Jalil says his country is grateful for help but will still need UN support
"Gaddafi is still in Libya and still possesses some resources that pose a threat not only to Libyans but to the international community as a whole," he said.
"The road before us is still long and there are many challenges at many levels. Our needs are many, we have lost 25,000 matryrs and there are double the number of wounded."
Addressing a high-level UN meeting on Libya on the sidelines of the General Assembly, Mr Obama praised the international community for having "the courage and the collective will to act" in Libya.
He said that the US ambassador was already on his way back to Tripoli.
"This week, the American flag that was lowered before our embassy was attacked will be raised again, over a re-opened American embassy."
He reassured Libyans that they could count on international support in the future.
"Just as the world stood by you in your struggle to be free, we will stand with you in your struggle to realise the peace and prosperity that freedom can bring," he said.
His comments come as Col Gaddafi issued a defiant audio message warning the opposition that Nato could not be counted upon.
It is the third audio message released by Col Gaddafi since he was ousted
"Do not rejoice and don't believe that one regime has been overthrown and another imposed with the help of air and maritime strikes.
"The bombs of Nato planes will not last," he said. It is not known when or where the audio message was recorded.
Broadcast on the Syria-based Al-Rai network, it is the third since he was ousted late last month.
Fighting continues for control of Bani Walid and Col Gaddafi's birthplace, Sirte, where pro-Gaddafi fighters are mounting fierce resistance.
Anti-Gaddafi forces launched an offensive on Bani Walid, 140km (90 miles) south-east of Tripoli, late last week, but were forced to retreat under heavy fire both times. Heavy clashes have continued since then.
Head of NTC revolutionary forces Gen Suleiman Mahmoud al-Obeidi told the BBC he had ordered fighters to change tactics at Sirte, pushing forward to capture Gaddafi loyalists' heavy weapons and then holding ground instead of retreating each evening.
He said he believed Col Gaddafi's brother-in-law and intelligence chief Abdullah al-Senussi is currently in the southern town of Sabha, trying to recruit more mercenaries to defend the area.
A significant number of tribesmen had crossed from Algeria into Libya earlier this week, although it was not clear whether they were being paid by Mr al-Senussi, who is wanted by the International Criminal Court over alleged war crimes, the general added.
Meanwhile, claims by Col Gaddafi's spokesman that loyalists had captured 17 foreign mercenaries during recent fighting have been denied by western powers and the NTC.
Moussa Ibrahim said on Monday that the mercenaries were "technical experts and consultative officers", adding that most were French, one was from an unidentified Asian country, two were English and one was from Qatar.
French Foreign Minister Alain Juppe said there were "no French mercenaries in Libya", while the British foreign office said it had no information about whether the report was true. Nato says it has no troops on the ground in Libya.