Tripoli, Libya (CNN) -- Libyan state TV reported Sunday that the opposition-held town of al-Bregahad been "been cleansed from the criminal gangs and mercenaries, the area is now safe, and all citizens should go back to their work and their normal life."

Forces loyal to Libyan leader Moammar Gadhafi have been fighting to recapture towns from the rebels since an uprising began last month.

Opposition leaders in Benghazi confirmed to CNN that their forces have left al-Brega, but they are calling their move a "tactical retreat."

The military has been pounding the key oil port of Ras Lanuf, once in the hands of rebel forces, and has taken control of towns such as nearby Bin Jawad. The Gadhafi government appears intent on retaking all territory from the opposition despite growing international pressure.

Libya's National Oil Corporation, meanwhile, urged companies to resume oil exports after saying that all ports are safe, state TV reported.

Also Sunday, the Maryland-based SITE Intelligence Group released a video in which it says Abu Yahya al-Libi, an al Qaeda leader, calls on Libyans to take up arms against Gadhafi.

The Libyan leader has frequently accused al Qaeda of being behind the unrest that began last month and has since spiraled into a civil war.

The Arab League voted Saturday to back a no-fly zone "to protect the civilian population" in Libya, the body's secretary-general Amre Moussa said.

"We will inform the U.N. Security Council of our request to enforce a no-fly zone over Libya," Moussa said. "The U.N. Security Council should decide how it will be enforced."

The Libyan foreign ministry denounced the League's move, calling it a "flagrant action against its charter," according to state TV Sunday. It also reported that the ministry would welcome the arrival of a fact-finding mission sent by some African nations.

Also Saturday, an Al-Jazeera cameraman was killed in an apparent ambush near Benghazi, Libya, becoming the first journalist killed in the country since the start of the civil war, the network reported.

Ali Hassan al Jaber was returning to Benghazi, an opposition stronghold in the east, from a nearby town where he had reported on an opposition protest when "unknown fighters opened fire on a car he and his colleagues were traveling in," Al-Jazeera reported on its English-language website.

The cameraman and another person were wounded. Al Jaber was rushed to a hospital, but did not survive, the network said.

"Al-Jazeera condemns the cowardly crime, which comes as part of the Libyan regime's malicious campaign targeting Al-Jazeera and its staff," the network reported.

The no-fly zone which the Arab League is calling for would be a preventive measure and would have to be stopped immediately when the Libyan crisis ends, Youssef bin Alawi bin Abdullah, Oman's foreign minister said in a joint appearance with Moussa.

Arab League members have reservations about military intervention, but said all countries agreed that a no-fly zone must be imposed urgently to protect civilians, bin Abdullah said.

"We hope the Libyan authorities will respect a no-fly decision," he said. "Be assured the Arab countries will not accept the intervention of the NATO coalition."

Moussa said the league also voted to open channels of communication with the Transitional National Council, the Libyan opposition's newly formed administration, and that any talks with that body would be on a humanitarian basis.

"We are giving them legitimacy but we're not giving them political recognition," Moussa said. "We are prepared to help evacuate any Arab nationals from Libya regardless of their nationality."

The Arab League also called for immediate humanitarian assistance and an end to the bloodshed in Libya, where war has broken out between forces loyal to Gadhafi and a tenacious opposition movement.

The White House cheered the League's announcements and stressed it will continue to pressure Gadhafi, support the opposition and prepare for "all contingencies."

Opposition forces made strides in the early days of the rebellion, but Gadhafi's military has recently gained strong momentum.

The League was meeting at its headquarters in Cairo, while hundreds of demonstrators outside urged the international community to step up support for Libyan opposition groups.

Pleading for international help as they continue to lose ground to pro-Gadhafi forces, rebels are asking for a no-fly zone that would theoretically thwart airstrikes.

No-fly zones are areas where aircraft are not allowed to fly. Such zones were put in place after the Gulf War in southern and northern Iraq as a check on the forces of the late Iraqi leader Saddam Hussein.

Western powers have said any action by the international community, including a no-fly zone, would have to have regional support and a clear mandate from the United Nations.

U.S. President Barack Obama said Friday that he "won't take (the) decision lightly" on whether to use military force, including helping to enforce a no-fly zone, saying it is critical to "balance costs versus benefits."

While France has recognized the National Transitional Council as the sole representative of the Libyan people, the European Union was more restrained Friday, saying it "welcomes and encourages the interim transitional national council based in Benghazi, which it considers a political interlocutor."

The Libyan government on Saturday took journalists to the eastern city of Bin Jawad, where the government ousted rebels about a week ago.

CNN's Nic Robertson said he saw fighter jets in the sky but he didn't see them engage in strikes.

He saw some structural damage, such as a blown-out police station and damage to a school and houses, including a Katyusha rocket embedded in the wall of a house. Some stores were closed and others had been looted.

CNN's Yousuf Basil and Reza Sayah and journalist Mohamed Fadel Fahmy contributed to this report.