The military forces supporting Libyan leader Moammar Gadhafi have driven rebels from one of their final strongholds, pushing about 40-kilometres deeper into opposition territory Sunday after hours of assault from air, land and sea.

The rebels, one of whom accused Gadhafi of taking the action before a no-fly zone was imposed by the United Nations, said they were fleeing the oil town of Brega under heavy attack -- leaving them with weaker fuel supplies and leaving Gadhafi's forces only 240 kilometres from the main opposition city of Benghazi.

A spokesperson for Gadhafi loyalists declared that they had seized control of Brega.

Speaking on condition of anonymity for fear of retaliation, one opposition fighter with responsibility for logistics said as he fled Brega for Ajdabiya and was now bracing for conflict there.

He said more fighters from rebel strongholds in the east were heading to Ajdabiya, the sole major population centre between his forces and the rebel headquarters, to prepare for a battle.

The rebels were trying to secure the southern and eastern roads to Ajdabiya and storing provisions and weapons there after the loss of free access to gasoline in Brega.

"There wasn't any time to breathe, to do anything," he shouted over the phone to the Associated Press. "I think they are bombing heavily because they want to win time before a no-fly zone is imposed."

If his string of successes continues, Gadhafi will soon face the choice of consolidating his control of the Mediterranean coast or moving swiftly toward Benghazi and the prospect of a devastating battle.

"Benghazi doesn't deserve a full-scale military action," army spokesperson Milad Hussein told reporters in the capital of Tripoli. "They are a group of rats and vermin and as soon as we go in, they will raise their hands and surrender."

Gadhafi's navy, army and air force began pounding Brega with artillery, rockets and bombs Sunday morning and didn't let up all day. A missile strike forced doctors and patients from the town's hospital, several rebels told The Associated Press after fleeing.

NATO closer to imposing no-fly zone

As Libya plunged further into civil war, NATO inched closer to imposing a no-fly zone over the region.

The stance of the military alliance, which includes Canada, the United States, France and Turkey, shifted on news that the Arab League has added its voice to the fray by requesting that NATO "shoulder its responsibility... to impose a no-fly zone over the movement of Libyan military planes and to create safe zones in the places vulnerable to airstrikes."

African approval for the controversial strategy is still being sought.

However, the U.S. and many allies have expressed deep reservations about the effectiveness of a no-fly zone, which would have to be approved by the UN Security Council, and the possibility it could drag them into another messy conflict in the Muslim world.

In a further sign of volatility, an al Qaeda commander who escaped from a U.S. prison urged Libyans to overthrow Gadhafi's regime and establish Islamic rule, the second time the terrorist network has addressed the uprising.

Abu Yahia al-Libi said in a video posted on a militant website that after the fall of the regimes in Tunisia and Egypt, it is now Gadhafi's turn.

He added that it would bring shame to the Libyan people if the strongman were allowed to die a peaceful death.

Gadhafi has accused al Qaeda of being behind the movement seeking to end his more than 40-year rule, though the rebels have no known links to the terrorist organization.

As fighting grows against the poorly equipped and loosely organized rebels, who had seized much of the eastern part of the country, the safety of reporters in the nation also became an increasing concern after an Al-Jazeera cameraman was slain in an ambush. He was the first journalist killed in the nearly month-long conflict.

Correspondent Baybah Wald Amhadi said the crew's car came under fire from the rear as it returned from an assignment south of Benghazi. Ali Hassan Al-Jaber was shot three times in the back and a fourth bullet hit another correspondent near the ear and wounded him, Amhadi said.

"Even areas under rebel control are not totally safe," he told The Associated Press. "There are followers, eyes or fifth columns, for Col. Gadhafi."

In another development Sunday, Libya's de facto oil minister said that the country's crude production has fallen "drastically" and that he has reached out to Italian oil giant Eni SpA for help in extinguishing a blaze at an eastern oil facility snatched back from rebel fighters.

Before the armed rebellion, Eni produced about 244,000 barrels of oil and gas-equivalent per day in the North African nation.

However the company, like other foreign oil companies, quickly withdrew its workers as the fighting escalated, bringing overall output down to roughly a third of its usual output.

With files from The Associated Press