The fugitive Gaddafi's exact whereabouts where still not known and it was possible he was still in hiding in Tripoli, five days after it fell to rebel forces and his 42-year-old reign collapsed.

NATO war planes struck at Sirte, on the Mediterranean coast, for a third day on Sunday, a spokesman for the multi-national alliance said in Brussels.

"We're paying close attention to what's happening in Sirte because we know that there are remnants of the regime that are there," the spokesman said.

On the ground, rebel forces also closed in and said they would seize Sirte by force if negotiations for its surrender failed.

One rebel commander said his forces were within 100 km (60 miles) of Sirte from the east and others were advancing from the west.

On the coastal highway east of Tripoli, tank transporters were carrying Soviet-designed T-55 tanks in the direction of Sirte. Rebels said the tanks were seized from an abandoned military base in Zlitan.