Libya's de facto premier Mahmud Jibril warned in his first address in Tripoli that the hardest battles are yet to come as fighters loyal to the new rulers closed in on Moamer Kadhafi's hometown Sirte.
China, which long propped up the fallen strongman and has extensive business interests in Libya, said on Friday it is ready to assist in the north African nation's reconstruction efforts.
"The battle of liberation is not finished," Jibril said late Thursday after National Transitional Council troops inching towards Bani Walid southeast of Tripoli came under rocket fire from old regime loyalists inside the oasis town.
The NTC has set a Saturday deadline for towns still loyal to Kadhafi to surrender, but Jibril warned that its troops would return to the offensive sooner if they continued to come under attack.
"We have the right to defend ourselves even before the deadline," he said.
On-off negotiations have been going on for days for the surrender of Bani Walid, where a number of former regime officials, including Kadhafi's spokesman Mussa Ibrahim, are believed to be holed up.
NTC fighters celebrated Thursday after they captured the Red Valley, 60 kilometres (40 miles) east of Sirte, one of the main lines of defence for Kadhafi's troops in Sirte, an AFP correspondent reported.
In defiant message on Thursday -- his first for several days -- the fugitive Kadhafi dismissed as lies reports that he had fled to neighbouring Niger, insisting he was still in Libya.
"They have nothing else to resort to apart from psychological warfare and lies," Kadhafi told the Damascus-based Arrai Oruba television.
"We are ready in Tripoli and everywhere to intensify attacks against the rats, the mercenaries, who are a pack of dogs," he said.
Jibril, who refused to speculate on Kadhafi's whereabouts, admitted that the battle for Libya's liberation would end only with the "capture or elimination of Kadhafi."
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The NTC fears Kadhafi will try to slip over one of Libya's porous borders, and Niger strongly denied he was there after a convoy carrying other senior ousted regime officials arrived on Monday.
In a bid to cut off Kadhafi's potential escape routes, the NTC said it had dispatched a team to the Niger capital Niamey, and Washington said Kadhafi aides who entered Niger were being detained.
None of those entering Niger earlier this week appeared to be on a list of persons subject to UN sanctions, US State Department spokeswoman Victoria Nuland said.
"Our understanding is that the convoy included some military and senior officials under Kadhafi's former regime," she said. "They are now being held in the capital... and they are being monitored closely by Nigerien officials."
Washington was also "in contact with Mali, Mauritania, Chad and Burkina Faso to emphasise the importance of respecting the UN Security Council resolutions and of securing their borders," Nuland said.
Niger Foreign Minister Mohammed Bazoum, speaking in Algiers, said neither Kadhafi nor any other wanted fugitives had arrived in his country.
Human rights group Amnesty International said Libya's neighbours must arrest Kadhafi and others wanted by the International Criminal Court (ICC) if they cross the borders.
"If they are found outside Libya, national authorities in that country must immediately arrest them and hand them over to the ICC to face trial for these crimes," said senior Amnesty director Claudio Cordone.
ICC prosecutor Luis Moreno-Ocampo has asked Interpol to help, his office said, by issuing a "red notice to arrest Moamer Kadhafi for the alleged crimes against humanity of murder and persecution."
As the fledgling interim government struggles to get Libya back on its feet, China on Friday vowed to lend a hand in reconstruction efforts.
"It depends on the needs of the Libyan people themselves, whatever they need we will be willing to help them," said Vice Foreign Minister Cui Tiankai, adding that China will support UN-led reconstruction efforts.
China is a major oil importer and needs to secure stable supplies of the resource to help keep its huge economy moving.
Libya produced about 1.6 million barrels of oil per day before the rebellion against Kadhafi broke out in February, but output has since slowed to a trickle.