National Transitional Council (NTC) forces say they have cornered loyalists of Muammar Gaddafi in a small area in the centre of Sirte, the hometown of the deposed Libyan leader whose whereabouts remain unknown more than six weeks after he was driven out of the capital Tripoli.
There are fears the fighting could breed long-term hostility, making it hard for the NTC to unite the vast North African state once the conflict is over.
Al Jazeera's Tony Birtley, reporting from Sirte, said the "noose has tightened around" pro-Gaddafi fighters but he added that they had "a lot of ammunitions and a lot of resolve".
NTC forces in Sirte took three important landmark buildings on Sunday - the main hospital, the university and the opulent Ouagadougou conference centre, built to host the summits of foreign dignitaries that Gaddafi was fond of staging.
"Eighty per cent of Sirte is now under our control," said Omar Abu Lifa, a commander of government forces attacking Sirte from the west.
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Desperate civilians were still trying to flee the fierce street clashes as fighting continued.
Shortly after NTC commander Javallah spoke, a group of three women, three small children and two male civilians emerged from a house on the front line. They were searched by NTC fighters and hurriedly got into a car and drove off waving the V-for-victory sign.
Another family of three women and one man, stopping at a checkpoint as they fled Sirte, said they had been trapped in their house by the fighting.
"We didn't know where the strikes were coming from. Everyone is being hit all day and all night. There is no electricity and no water. There's nothing. There's not one neighbourhood that hasn't been hit," said one of the women, who gave her name as Umm Ismail.
Battle for Bani Walid
Gaddafi supporters also still hold the inland enclave of Bani Walid, where NTC forces also reported key gains after weeks of faltering advances that resulted in part from the challenging terrain of desert hills and steep valleys.
|Al Jazeera has the latest on the fight for Bani Walid|
Meanwhile, a group of more than 200 gunmen attacked a mosque in Tripoli and ransacked the tombs of two imams, witnesses said on Monday.
"They arrived shortly after 10pm (2000 GMT, Sunday night), between 200 and 300 of them, in pickup trucks fitted with heavy machineguns. They took off at about 1am," said Mahmud Rahman, a resident of Tripoli's northeastern Al-Masri district.
"They forced open the mosque's door and then started to dig up the tombs of imams Abdel Rahman el-Masri and Salem Abu Seif, and made off with their relics," said Rahman.
An AFP journalist, visiting the mosque and its adjoining Quranic school, said Muslim holy books had been burnt.
The NTC forces have been trying for a month to gain control of Bani Walid, an oasis in rugged terrain where Gaddafi loyalists have been putting up fierce resistance.
NTC commanders are convinced that Gaddafi's most prominent son, Seif al-Islam, is in the town, as well as possibly the deposed strongman himself.