Gaddafi sends a message of defiance to supporters as the battle rages for Tripoli

As his capital was wrestled from him after days of ferocious fighting, Muammar Gaddafi issued a defiant message from his hiding place yesterday urging his supporters to "purify" Tripoli as 1,000 rebel fighters bombarded the regime's remaining enclave in the city.

An angry Gaddafi denounced the "rats, crusaders and unbelievers" in an audio message broadcast by satellite television channels during another day of brutal combat in Tripoli. There was no sign of an end to the conflict as the battle raged for four hours in the battered neighbourhood of Abu Salim, amid rumours that some of Gaddafi's family or even the dictator himself could be ready to launch a final stand from a loyalist enclave in a block of flats.

While the UN Security Council was agreeing to release £1bn of seized Libyan assets for humanitarian aid, the discovery of a grim pile of corpses of executed men in the Bab al-Aziziya compound which had once been Gaddafi's citadel offered grim evidence of retribution being exacted in the bloody civil war. A dozen bodies were seen lying inside the complex with their hands tied behind their backs.

"Mercenaries, mercenaries," shouted a group of shabab (youths), as armed volunteers pointed at the dead men. The opposition had accused Col Gaddafi of hiring gunmen from sub-Saharan Africa during the conflict and many of those captured had been killed.

Fresh skirmishes broke out in the centre of Tripoli during which the Corinthia Hotel, used by foreign journalists, came under fire. There was also a surge of excitement in the shabab ranks after a house where Gaddafi had supposedly taken refuge was surrounded, although no attempt was made to force entry by the early evening.

Outside Tripoli, Libya's eastern rebels advanced on Sirte, Gaddafi's hometown, in the hope of driving loyalists from the most significant city remaining in their control. After overnight raids by Nato warplanes, which destroyed a group of Scud-missile support vehicles outside of Sirte, the approaching rebels were said by officials in Benghazi to be negotiating with tribal leaders to enter the city peacefully.

"The issue of Sirte is complicated," the rebel Transitional National Council's defence spokesman, Col Ahmed Bani, told Bloomberg. "The power has been cut off so that the residents don't know what's going on around them or that Gaddafi is on the run."

But local radio broadcasts picked up by the BBC claimed that Gaddafi forces were executing rebel prisoners and burying them in a mass grave.