Forces loyal to strongman Muammar Qadaffi unleashed a fierce assault on a rebel stronghold in the mountains of western Libya, a former Libyan general told Reuters on Friday.

The offensive, described as the largest Qadaffi has launched against the rebels to date, began at dawn Thursday, the former general said. He now commands rebels in Zintan, using the name Hajj Usama.

Qaddafi's forces simultaneously attacked Thursday on three fronts, Hajj Usama said -- to the north of Zintan, firing Grad rockets into the eastern part of the nearby town of Rayayna, and attacking to the southeast and to the east of Zintan.

The Qadaffi force consisted of about 150 infantry supported by some 40 vehicles including the rocket launchers.

Zintan lies about 90 miles southwest of the capital, Tripoli, at the eastern tip of a 170-mile ribbon of rebel-held mountains that stretch westward from the Tunisian border. The region has been the site of back-and-forth fighting between Qadaffi and rebel forces over the past month.

After decades in the Libyan army, including a tour of duty in neighboring Chad, Usama said he now despises his former commander in chief, whom he called a terrorist.

"He's never used infantry like this," said the trim, gray-bearded rebel commander. In previous battles, Hajj Usama said, Qadaffi's artillery forces had taken over nearby civilian housing in Zuwail al Bagul and shelled from a distance.

In response, Hajj Usama said he dispatched hundreds of fighters to cut off Qaddafi's advance.

As of Friday night, one rebel was dead and three were wounded, one of them critically, he said.

Some of the fighters who returned late Friday from the front lines -- crammed into the backs of pickup trucks -- appeared to be school-age. They carried only a handful of weapons, a few hunting rifles and old, bolt-action shotguns.

Nevertheless, Hajj Osama said, "they are keen and determined to fight for their freedom."

Since the raids began, Hajj Usama said, he has lost contact with rebels in Rayayna with the exception of one commander who managed to make the dangerous journey to Zintan after his house was destroyed in the shelling.

As dusk fell Friday the shelling visible earlier from the roofs of Zintan abated. But shortly before 10 PM., the attack resumed with sporadic barrages of gunfire.

Qadaffi's offensive comes as the Western stance softens with both France and the United Kingdom now saying perhaps Qadaffi can stay.

Just six days ago the US had said in no uncertain terms Qaddafi 'must go' before any resolution to the conflict would be discussed.