Muammar Gaddafi's forces fired artillery at rebels regrouping outside the strategic eastern city of Ajdabiya today, forcing them to scatter and signalling a prolonged battle.

A ragtag band of hundreds of fighters on the outskirts of Ajdabiya milled about, clutching mortars, grenades and assault rifles.

The group was forced to flee in jeeps and trucks when they came under fire from regime forces but later returned and clustered in the same area - a pattern that has become common as the rebels fight to seize the momentum as the regime's forces and air defences are pounded by international strikes.

Disorganisation among the rebels could hamper their attempts to exploit the turn of events.

A rebel commander who defected from the Libyan special forces said a lot of professional ex-soldiers also had poured into Ajdabiya and the nearby oil port city of Brega, encircling the Gaddafi forces to disrupt their supply lines under Western air cover.

"If not for the West we would not have been able to push forward," said Ahmed Buseifi, a 32-year-old dressed in fatigues and boots. "I'm pinpointing where their forces are and their tanks and passing it up the chain of command."

He complained the large number of so-called citizen soldiers were only getting in the way.

"It's making it difficult to do our job. It's important to take care of their lives," he said.

The Western air campaign that began on Saturday has unquestionably rearranged the map in Libya and rescued rebels from the immediate threat they faced only days ago of being crushed under a powerful advance by Gaddafi's forces.

Last night Libyan state TV said a new round of strikes had begun in the capital, Tripoli, marking the third night of bombardment. But while the airstrikes can stop Gaddafi's troops from attacking rebel cities - in line with the UN mandate to protect civilians - the United States, at least, appeared deeply reluctant to go beyond that toward actively helping the rebel cause to oust the Libyan leader.

US Defence Secretary Robert Gates and others said the US military's role will lessen in coming days as other countries take on more missions and the need declines for large-scale offensive action.

In his first public comments on the crisis, Army Gen. Carter Ham, the lead US commander, said it was possible that Gaddafi might manage to retain power.

"I don't think anyone would say that is ideal," the general said, foreseeing a possible outcome that stands in contrast to President Barack Obama's declaration that Gaddafi must go.