World leaders were to meet in Paris on Thursday to plot Libya's post-Kadhafi future as one of the fugitive dictator's sons pledged that loyalists would fight their rebel enemies to the death.
The message of defiance punctured a festive mood in Tripoli at the end of Ramadan but the announced capture of Kadhafi's foreign minister Abdelati al-Obeidi gave succour to those seeking to consign the regime to history.
There has been no firm word on Kadhafi's whereabouts since he appeared on television 11 days ago, although there is much speculation that he is holed up in either his stronghold of Sirte, the desert, or in a suburb near the capital.
Thursday's conference in the French capital, which will be attended by delegates from 60 countries, is expected to discuss funding for Libya as well as police training and diplomatic recognition for its new rulers.
US Secretary of State Hillary Clinton will be in Paris to sound out the rebels on what officials in Washington describe as their "enormous" needs as they try to establish a new government in Tripoli.
The "credibility" of the National Transitional Council (NTC), the political umbrella for the rebels, rests on such achievements, a senior US official told reporters on condition of anonymity on Wednesday.
The NTC is recognised by the United States and dozens of other countries as Libya's interim governing authority, but how well the rebels can bring security to Tripoli and deal with running a country remain in doubt.
Urgent needs in Tripoli -- where Kadhafi forces were overrun in fierce battles more than a week ago -- are water, food, gasoline and electricity, officials say.
"The needs are enormous. Kadhafi has left them... with a shattered country," the US official said. How to deal with Kadhafi if he is finally captured following a six-month revolt is also a worry for world leaders.
Mustafa Abdel Jalil, chief of the NTC said in an interview published on Wednesday by Egypt's state-owned Al-Ahram newspaper he wanted Kadhafi arrested alive so he could face justice.
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Clinton's participation in what has been dubbed the "Friends of Libya" conference comes as the rebels try to wipe out the last pockets of resistance from Kadhafi fighters.
The dictator's best known son, Seif al-Islam, who has rapidly become his father's most visible defender, told the Damascus-based Al-Rai television station in an audio message aired Wednesday that there would be no surrender.
"The leadership is fine and the leader is fine," he said. "I am talking to you from a suburb of Tripoli. We want to reassure the Libyan people that we are still here. The resistance continues and victory is near."
Seif al-Islam warned the rebels against any attack on his father's hometown of Sirte, the last major centre in loyalist hands.
"They're welcome if they think the battle of Sirte will be a walkover. Twenty thousand armed men are in the town and ready," to fight, he told Al-Rai.
However, another much less powerful Kadhafi son, Saadi, appeared to express a readiness to surrender as the rebels said they had captured Kadhafi's foreign minister, although few details were given.
"Yes, Abdelati al-Obeidi was arrested today," Mahdi al-Harati, vice chairman of the rebel military council, told journalists in the capital on Wednesday, without elaborating.
But Harati did confirm that negotiations had been opened on the surrender of Saadi.
"He is reluctant but, if he wants to surrender, his life will be safe, God willing. If there is an agreement, there will be no problems."
Earlier, Saadi Kadhafi told the Al-Arabiya channel in an audio interview that he had "no problem" with the rebels ruling Libya.
"If my surrender stops the spilling of blood, I am ready to give myself up tonight," he said.
Rebel military spokesman Colonel Ahmed Omar Bani has said his forces are "ready for a final military battle," describing Saturday as "zero hour."