Sirte was rocked by deadly fighting on Friday in what new regime forces said was a final assault on Muammar Gaddafi's besieged hometown, with orders they take it the same day despite stiff resistance.

By mid-afternoon, sustained mortar, machinegun and sniper fire was preventing National Transitional Council (NTC) forces from overrunning the Ouagadougou conference centre, a major bastion of pro-Gaddafi forces in the west of the city. As ambulances streamed in to a field hospital nearby, its administrator said 10 fighters were killed and 150 wounded.

Ahmed Mohammed Abu Oud also said that four ambulances had been destroyed by fire from Gaddafi forces, and two ambulance workers wounded.

There were no immediate casualty figures from the eastern side of the Mediterranean city, 360 kilometres (225 miles) east of Tripoli, where morning fighting raged in and around the university, another Gaddafi stronghold.

After a ferocious dawn barrage of artillery and rocket fire, hundreds of fighters tried to enter the city in columns of pick-up trucks mounted with anti-aircraft and machineguns.

Sustained NTC tank and mortar fire hit targets in the city, with much of it concentrated around the Ouagadougou centre. But resistance was fierce and effective, NTC sources said.

NTC commander Nasser Abu Zian told the media that most of the ground troops had pulled back, with the centre constantly shelled by 106 mm cannon and anti-aircraft guns on pickups. "The fighters went in three ways today," he said. "The Benghazi fighters went in from the east and we from the south and west."

"We are surrounding them in the centre of the city in an area of just a few square kilometres."

Plumes of black smoke could be seen billowing up from several points in the city, amid the sound of machinegun fire and explosions. NATO planes flew overhead, but there were no reports of air strikes.

NTC fighter Barak Abu Hajar told the media that he had been in action earlier at the Ouagadougou centre and brought out a wounded comrade. "They're shooting from everywhere. RPGs and lots of bullets. We were told this was the final assault. Inshallah (God willing) we will take Sirte today."

Fighter Faisal Asker said, "We entered the Ouagadougou centre compound but fell back because of RPG (rocket-propelled grenade) and sniper fire. There's no cover there. We have orders to finish the mission today."

More casualities

At the field hospital, just a couple of kilometres away from the Ouagadougou centre, the AFP reporter said ambulances with wailing sirens were arriving every couple of minutes.

A man with a loud hailer, joined by others, shouted ‘Allahu akbar’ (God is greatest) every time a patient was taken inside the derelict building housing the hospital.

A white minivan arrived and a crowd gathered round in prayer. Inside there were four bodies wrapped in grey blankets, tied with white tape and a large white sticker giving their names.

The reporter saw five other dead, including the remains wrapped in a blanket of one person whose body medics said had been blown apart by shrapnel.

Sirte and Bani Walid, a desert town 170 kilometres (100 miles) southeast of of Tripoli, are Gaddafi's last major bastions against the NTC, which has ruled most of the oil-rich country since the veteran strongman was toppled in August.