Anis Sharif says Gaddafi is still in Libya, and has been tracked using human intelligence and technology.
Sharif refuses to say where he is, but says he is trapped in a 60-kilometre radius area surrounded by rebels, can't get out, and the former rebels are preparing to detain him or kill him.
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The statement comes as a TV channel claims Gaddafi and his son Seif al-Islam are in Libya and in good spirits.
BATTLES LOOM
Meanwhile, the new leaders warned of a "fierce battle" for pro-Gaddafi bastion Bani Walid after a truce deal foundered, as top officials of the ousted dictator's regime sought refuge in Niger.
Optimism that loyalist troops controlling Bani Walid would lay down their arms and allow National Transitional Council (NTC) fighters to roll in dissipated late Tuesday when tribal elders who negotiated the truce were barred from re-entering the town.
"I think there will be a fierce battle in Bani Walid. Armed groups are occupying Bani Walid so we must free it," NTC military commander Colonel Abdullah Abu Asara told AFP.
Witnesses reported seeing the tribal elders heading away from Bani Walid, 170 kilometres (105 miles) southeast of Tripoli, towards the nearby town of Tarhuna late on Tuesday.
The elders had earlier met with NTC officials in a mosque in the village of Wishtata on the outskirts of Bani Walid for a new round of talks after negotiations for the town's surrender collapsed on Sunday.
