The rebels, who have been moving troops toward remaining Gadhafi bastions across Libya, had shifted the deadline for the town of Sirte in hopes of avoiding the bloodshed that met their attack on Tripoli.
"We want to save our fighters and not lose a single one in battles with Gadhafi's forces," said Mohammed al-Rajali, a spokesman for the rebel leadership in the eastern city of Benghazi. "In the end, we will get Sirte, even if we have to cut water and electricity" and let NATO pound it with airstrikes.
World leaders meeting in Paris on Libya's future after Gadhafi said the NATO military operations would continue as long as needed.
The rebels say the advance on Sirte is going well, and that their forces have already captured one nearby city. They also say they are closing in on Gadhafi, who came to power 42 years ago Thursday in a military coup that toppled King Idris.
The rebels have been hunting for Gadhafi since he was forced into hiding after they swept into Tripoli on Aug. 20 and gained control of most of the capital after days of fierce fighting.
"We won't surrender again; we are not women. We will keep fighting," Gadhafi said in a blustery tone in the audio statement, broadcast by Syrian-based Al-Rai TV. His voice was recognizable, and Al-Rai has previously broadcast statements by Gadhafi and his sons.
Gadhafi said the tribes in Sirte and Bani Walid are armed and "there is no way they will submit." He called for continued resistance, warning "the battle will be long and let Libya burn."
In a second late-night audio also broadcast on the Syrian channel, Gadhafi spoke in more measured tones and called for a long insurgency.
"We will fight them everywhere," he said. "We will burn the ground under their feet."
He said NATO was trying to occupy Libya and steal its oil. "Get ready to fight the occupation. ... Get ready for a long war, imposed on us," Gadhafi added. "Get ready for the guerrilla war."
He called Sirte "the capital of the resistance."
The rebels, who have effectively ended Gadhafi's rule, dismiss his threats as empty rhetoric.
The rebels believe he may be in one of their three key targets. The rebel fighters, backed by NATO airstrikes, have been pushing in recent days toward Sirte as well as toward Bani Walid, 90 miles (140 kilometers) southeast of Tripoli, and the southern city of Sabha.
All three were given a Saturday deadline to surrender. While the deadline extension was officially only for Sirte, rebels said it would also apply to Bani Walid and Sabha.
Pro-Gadhafi forces control most of Sabha and large numbers of soldiers - including mercenaries from other African countries - are camped on its outskirts, said Abdul Awidat, a Sabha resident currently in Tripoli.
Awidat told The Associated Press that he has spoken by satellite phone with people in the southern area in the past two days who said pro-Gadhafi forces have taken up positions in buildings and are recruiting young men as fighters and handing out weapons.
"There is no information that Gadhafi or any of his senior leadership are in Sabha," he added.
Some anti-government protesters have taken over a small part of the town of Gorda, and there has been fighting in the area with several people killed, Awidat said.
He said there is no electricity, running water or regular telephone service, and medicine is running out.
In a boost to the rebel cause, the last prime minister under Gadhafi said he now supports the opposition.
Al-Baghdadi al-Mahmoudi told Al-Arabiya television that had had been in contact with the rebels "and we notified them that we are with the people and we are ready to serve our country in the future."
Meanwhile, Ahmed Said, an adviser to the interior minister in the rebels' interim government, said Gadhafi's foreign minister had been captured. He did not identify him by name, but "can confirm that he is in custody." A week ago, Foreign Minister Abdul Ati al-Obeidi told British broadcaster Channel 4 that Gadhafi's rule was over.
Algeria, which gave refuge to Gadhafi's wife and three of his children this week, has indicated it will not do the same for the longtime dictator.
The Algerian newspaper El Watan reported Gadhafi had also sought sanctuary in Algeria, but the president refused to take his phone calls. Asked Thursday if Gadhafi could be given asylum, Algerian Foreign Minister Mourad Medelci said: "I don't believe so."
In Paris, world leaders and top-level diplomats from 60 nations lined up behind the new government and focused on unfreezing billions in Libyan funds held abroad.
British Prime Minister David Cameron said NATO will continue operations for as long as necessary to protect civilians in the North African country. U.N. Secretary-General Ban Ki-moon urged the Security Council to decide quickly on deploying a civilian mission to stabilize Libya.
"We cannot afford a failed pariah state on Europe's borders," Cameron said. "We will all lose if the Arab Spring gives way to a cynical winter of repression."
Rebel leader Mustafa Abdel Jalil said Libya's new government must ensure "that we fulfill our side of the deal - we must have security in Libya, tolerance and forgiveness must be promoted, the state of law must be respected."
Russia, which had criticized the NATO operation, recognized the rebels as Libya's interim leadership hours before the talks began.
The European Union is lifting its sanctions on Libyan ports, banks and energy firms to provide resources to the interim government to help kick-start its economy, officials said.
Michael reported from Cairo. Associated Press writers Rami al-Shaheibi in Benghazi, Libya, Jamey Keaten in Paris and Martin Vogl in Bamako, Mali, contributed to this report.