Tripoli/Washington: Libyan forces showed no signs of relenting despite air strikes by western warplanes for the sixth day on Thursday. Libyan forces on Wednesday night hammered rebel stronghold Misurata and other towns, forcing people to flee.

Heavy shelling by forces loyal to Muammar Gaddafi was reported in the rebel-held Misurata and fierce fighting with opponents in strategic Ajdabiya.

Residents fled the towns to escape shelling and gunfire. Rebels claimed that several houses were on fire after the shelling.

Gaddafi's forces also resorted to sniper firing to dislodge the rebels.

Witnesses were quoted as saying that in Misurata, Libya's third-largest city, that tanks had withdrawn from their positions in the wake of air attacks by western forces but had later rolled back to resumed shelling.

Eight explosions rocked Tripoli. An explosion was also reported at a military base in the Tajura region, east of the capital.

The Gaddafi regime has accused the coalition forces of killing civilians, a charge refuted by the western nations.

18 charred bodies were shown to a group of journalists who were taken to a hospital early today and government claimed they were of military personnel and civilians killed in the air strikes.

US and allied forces shifted focus on hitting Libyan ground forces, targeting tanks and artillery.

The shift to attack the ground forces came after coalition commanders claimed that Gaddafi's air force had been completely destroyed and that the US and NATO warplanes had total sway of the Libyan sky.

The massive strikes on Gaddafi's ground forces, including his big Armada of tanks, mobile rocket launchers, heavy guns and short range battle missiles, mark the second phase of operation 'Odysses Dawn', British Air Vice Marshal Greg Bagwell said.

Gaddafi's air force "no longer exists a fighting force," Bagwell said as a flotilla of NATO warships patrolled Libya's coast to enforce an arms embargo against Gaddafi.

As the allied operation entered the sixth day, French Foreign Minister Alain Juppe said the campaign would continue.

"It will last for days and weeks. But, not months," he said, spelling out for the first time the expected duration of the military campaign.

The French Minister was speaking to reporters in Brussels ahead of a crucial EU-NATO meeting to discuss how to coordinate airstrikes on Libya.

Coalition forces also struck hard at Gaddafi's forces Adjabiya and Zintan. "We are interdicting and putting pressure on Gaddafi's forces that are attacking population centres," said Rear Admiral Gerard P Hueber, the Chief of Staffs for the American-led operational command.

"The air attacks continued day and night yesterday and resumed this morning on Gaddafi's ground forces in both Misurata in the west and Adjabiyah in the east," the Admiral said as NATO's top military commander US Admiral James Stavridis flew into Turkey to hold talks with Turkish military leaders who are holding up an agreement for NATO to take over command of Operation Odyssey.

The allied forces also continued Tomahawk missile strikes and air bombing of the Libyan capital Tripoli.

The official JANA news agency said coalition raids on Tajura, 32 km east of the capital, had killed a large number of civilians. Tajura, which houses a massive military complex, including a missile base, has been hit thrice.

JANA said the latest raid had targeted rescue workers who were trying to remove the dead and wounded from the rubble left by the first two raids.

Although the endgame in Libya remains unclear, US Defence Secretary Robert Gates, now on a farewell visit to Egypt, said that mounting pressure on Gaddafi could encourage his inner circle and even members of his family to turn against him.

"I think there is any number of possible outcomes here, and no one is in a position to predict them," Gates said.

A US commander said the allies flew 175 sorties in 24 hours, and the US flew 113 of those. French Defence Minister Gerard Longuet, meanwhile, said France had destroyed about 10 Libyan armoured vehicles over three days.

However, there was no let up in Gaddafi forces' shelling of the rebel-held cities.