Meanwhile, National Transitional Council (NTC) fighters were gearing for a fresh onslaught on the desert town of Bani Walid, another remaining bastion of forces loyal to the ousted dictator, prompting civilians to flee.

In Sirte, jubilant NTC combatants celebrated the takeover of the strategic police building, which they found to be deserted, by honking the horns of their vehicles and firing into the air.

They then proceeded to ransack the centre and destroy posters of the fugitive Kadhafi that they found inside.

The celebrations came to an abrupt end when one of the fighters was accidentally shot in the head, an AFP reporter said.

In contrast to Monday, when NTC forces were pounded with rockets and gunfire as they battled Kadhafi loyalists street by street, they met no resistance at all on Tuesday as they edged into the centre of the Mediterranean city.

An advance force of about 30 fighters checked each house as they moved forward from the city's east early morning, kicking in doors and covering each other from possible snipers hidden on rooftops.

Clothing abandoned by soldiers and remains of meals were found in some of the buildings.

The fighters became more cautious once they reached the city centre, sticking to its edges for fear that snipers were lying in wait inside and on top of the many tall buildings.

They then converged on the nearby police headquarters, expecting a battle but found it empty.

Early afternoon, fighting erupted southwest of the central square, a vast esplanade that dominates the city, an AFP reporter said.

Fighters who had taken over the police headquarters regrouped and were seen heading in that direction.

On Sunday, NTC troops captured Sirte's showpiece conference centre, as well as its university campus and main hospital, AFP correspondents said.

The NTC fighters had besieged Sirte from September 15 before launching on Friday what they termed a "final assault" that has seen at least 70 of their number killed and hundreds wounded, according to medics.

Wissam bin Ahmid, commander of NTC forces on Sirte's eastern front, said early Tuesday his fighters were close to overrunning the entire city but still feared for the safety of many civilians too scared to flee the fighting.

"There remains still two square kilometres (0.8 square mile) to take to free the city completely," Ahmid told AFP.

"There are still some snipers. But our main worry are the families still in the city who are too afraid to leave their houses as the snipers are using them as firing posts," he said.

In Bani Walid, a desert oasis 170 kilometres (105 miles) southeast of Tripoli, the military said NTC fighters withdrew from forward positions in a "tactical pull back" after intense fighting on Sunday.

"We lost 17 fighters in fierce clashes on Sunday and our forces have withdrawn from the airport where they had taken control," said Salem Gheith, head of the NTC military command centre in the capital.

"We've received reinforcements from Tripoli and the Nafusa mountains, and we will resume the offensive," he said.

Regional NTC commander Yunes Mussa announced the airport's capture on Sunday, before the fightback by pro-Kadhafi forces.

Civilians fearing more clashes were fleeing Bani Walid on Tuesday, an AFP reporter on the edge of town said.

According to fighters stationed at Shumayh checkpoint near the oasis, between 20 and 25 civilian vehicles had passed through by mid-morning.

"We hear that there will be fighting. In the town, there is no doctor, no water, no electricity," said a man in a white Mitsubishi that also carried four veiled women.

"There are mercenaries and militia in the streets," said the man, who was taking his family to Nasmah, west of town, where there is a camp for those displaced by the fighting.

A van loaded with mattresses and a pickup truck carrying sheep sat behind him in line.

NTC fighters distributed fruit juice and sweets to the families fleeing the town.

NATO said its warplanes struck three armed vehicles in Bani Walid on Sunday, and three stores containing ammunition and/or vehicles on Monday.

Its secretary general, Anders Fogh Rasmussen, said the alliance was close to terminating its mission in Libya.

"We are pretty close to the very end of this operation," Rasmussen said in Bucharest.

Despite the NTC's advances in Sirte, he said NATO "had no knowledge of the colonel's whereabouts," adding that Kadhafi "is not a target of our operation."

NTC commanders believe one of Kadhafi's sons, Mutassim, is in Sirte and that another, Seif al-Islam, once seen as the former strongman's successor, is hiding in Bani Walid, possibly with his father.

Copyright AFP (Agence France-Presse), 2011