NATO has launched a bombing campaign on Muammar Gaddafi's hometown of Sirte to clear the way for fighters supporting Libya's interim government to advance deeper into the city and gain control.
The forces of the National Transitional Council (NTC) prepared to renew their advance into the coastal city on Monday, a day after the roar of jet engines and sporadic booms could be heard as NATO ordnance hit targets on the ground.
One strike, giving off a deep thud, released a big cloud of smoke and dust over the south of the city.
"NATO has dropped a lot of bombs today," said one NTC fighter, who declined to give his name. "You can see the planes up above. They struck along here," he said, gesturing with his hand across the area south of the city centre.
Earlier this weekend, NTC forces had pushed to within a few hundred metres of the centre of Sirte - one of the last bastions of pro-Gaddafi resistance in Libya - but later drew back to let the NATO jets do their work.
"Yesterday our freedom fighters attacked Sirte city from two sides. That doesn't mean that Sirte is free now, but it is an indication that Sirte will be free soon," said Ahmed Bani, an NTC military spokesman in Tripoli.
"I'm asking now any militiamen fighting on the side of the tyrant [to realise] that the game is over."
NATO's support for the anti-Gaddafi rebellion played a major part in toppling Gaddafi and the alliance says it will keep up its operations for as long as needed.
In a statement, the alliance said its sorties in the vicinity of Sirte had struck targets that included two command and control facilities, a military staging area, a storage bunker and radar facility, and 29 armed vehicles.
Meanwhile, many residents of Sirte have taken advantage of the relative lull in fighting to flee the city.
While many residents have claimed that Gaddafi's troops are attempting to prevent civilians from leaving, a Gaddafi spokesman has accused NATO of killing several hundred civilians in strikes on the city.
Refusing calls to surrender, Gaddafi loyalists holed up in Sirte are putting up stiff resistance.
Al Jazeera's Zeina Khodr, reporting from the city's outskirts, said NTC fighters were forced to pull back earlier this week "after a fierce and intense battle. Both sides were using heavy power".
An NTC commander told our correspondent that the forces retreated because there were not enough to hold territory, and they had endured a high casualty toll among their ranks.
"In fact the casualty toll on Saturday was nine dead among the anti-Gaddafi fighters and up to 97 wounded, mostly as a result of snipers' fire," Khodr said.
"We have to remember these are inexperienced fighters."
Khodr added that NTC commanders are adamant that they were not "forced" to pull back from Sirte's centre.
"They are calling it a tactical retreat," our correspondent reported.
Gaddafi loyalists, also acting tactically, launched an attack on the desert oasis town of Ghadames on Sunday, where they plan to re-group and re-arm, NTC officials said.
Besides Sirte, Bani Walid remains the only other major urban area left under Gaddafi's control.
Abu Salim massacre
Meanwhile, Libya's new rulers revealed the discovery of a mass grave believed to hold the remains of more than 1,200 people in the Libyan capital.
Khalid Sharif, a spokesman for the NTC's military council, said the bodies were those of prisoners who were executed at Tripoli's notorious Abu Salim jail in 1996 - though it was not immediately possible to verify the claim.
"We found the place where all these martyrs were buried," said Sharif, adding it was evidence of "criminal acts" by Gaddafi'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 massacre of the inmates helped trigger the revolt in February, when families of Abu Salim victims in the eastern city of Benghazi 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 Gaddafi's regime to come clean about the fate of prisoners killed at the jail.