Libya's new rulers said they have unearthed a mass grave of 1,700 prisoners slain by Moamer Kadhafi's regime in a 1996 uprising, a massacre that helped trigger the revolt that ousted the despot.

The gruesome find came as hundreds of the National Transitional Council's fighters thrust into Kadhafi's hometown of Sirte from the east and NATO warplanes pounded the coastal city for a second straight day.

The remains of the prisoners executed at Tripoli's notorious Abu Salim jail were found in a mass grave in the capital, said Khalid Sharif, spokesman for the NTC's military council.

"We found the place where all these martyrs were buried," said Sharif, adding it was proof of "criminal acts" by Kadhafi's regime.

Salim al-Farjani, a member of the committee set up to identify the remains, appealed for international help.

"We call on foreign organisations and the international community to help us in this task of identifying the remains of more than 1,700 people," said Farjani.

The first demonstrations in Libya which finally ousted Kadhafi last month erupted in Benghazi in February, when families of Abu Salim victims called for protests against the arrest of their lawyer.

Farjani said he witnessed the gruesome site where the Abu Salim victims were found.

"We were invited to visit the place where the corpses of the prisoners at Abu Salim were found, where we saw scattered human bones," he said.

Farjani also referred to "egregious acts committed against dead bodies, on which acid was poured to eliminate any evidence of this massacre."

International rights groups had for years urged Kadhafi's regime to come clean about the fate of prisoners killed at the jail.

On the warfront, NTC fighters flashed V-for-victory signs and shouted "Allahu Akbar" (God is greatest) as they moved into Sirte on pickup trucks and larger lorries, backed by three artillery tanks.

"Our forces are around 10 kilometres (six miles) inside Sirte" from the eastern gate, said commander Ahmed Zlitni from the NTC operations centre, as he emerged from the gate Sunday with a group of fighters.

As fighters rolled in from the eastern gate, two ambulances sped out with sirens ablaze, and other NTC fighters emerged from the Kadhafi bastion, where they said there were gunbattles.

"We are fighting with Kalashnikovs and small arms around the city centre," Mar'ee Saleh of the Ali Hassan Jabar Brigade told AFP.

"We are firing at Kadhafi's men but their return fire is not very strong," he said as he left the eastern entrance, adding he saw NATO warplanes carry out strikes during the day.

Many of the pickup trucks entering the city carried food and water supplies, as well as mattresses, an indication the fighters were planning to take stranglehold positions inside Sirte, the correspondent said.

"There are clashes inside the city. Two small girls were killed today when a Grad rocket fired by Kadhafi forces hit a home in Sirte," said Makhluf al-Farjani, spokesman of Sirte's military council.

On Sirte's western outskirts, NTC forces held their ground saying they had received instructions not to launch a fresh assault on Sirte to allow NATO to carry out operations.

NATO aircraft launched at least a dozen air strikes around Sirte on Sunday morning, an AFP correspondent said.

One Sirte resident who managed to flee early on Sunday said fighting subsided at around 7:00 pm on Saturday.

"There are African mercenaries roaming across the city. They are firing at houses with anti-aircraft guns in district one" on the western edge of Sirte, he said.

He also said he twice saw one of Kadhafi's sons, Mutassim -- once in a command centre in a hospital basement -- during the past three weeks.

Frontline fighters in Sirte have repeatedly said Mutassim is holed up in its southern outskirts.

The assault on Ghadames, 600 kilometres (370 miles) southwest of Tripoli, came at dawn, killing at least eight NTC fighters and wounding 50, said Muhandes Sirajeddin, deputy chief of the local council.

"The attack began at around 5:30 am (0330 GMT). Around 100 Kadhafi loyalists, including mercenaries who came from around Algeria (across the border), and groups of Tuareg took part in the fighting," he said.

Sirajeddin and two other residents said clashes were still under way in Ghadames, a UNESCO World Heritage Site and home to Roman ruins.

Heavy fighting also raged in Bani Walid, the only other remaining pro-Kadhafi bastion, with NTC fighters coming under fire from inside the town, an AFP correspondent said.

NTC commander Omar Mukhtar said his men are "regrouping" but would not attack on Sunday.

NTC forces believe that Kahdafi's most prominent son, Seif al-Islam, is holed up in Bani Walid. "We know exactly where he is," Mukhtar said.