Al-Masdar Online, an independent website, posted a video showing the aid workers who were taken hostage on May

Al-Qaeda fighters have freed three French aid workers they kidnapped in Yemen more than five months ago, the French presidency and tribal sources have said.

"The president was informed tonight of the liberation of the three aid workers held in Yemen since May 28, 2011," the presidential palace said in a statement early on Monday.

A tribal chief involved in negotiating the trio's release, said they were in good health.

"They are with me in Ataq, an hour after they were freed by al-Qaeda," he said. Ataq is the administrative capital of Yemen's southern province of Chabwa.

France "warmly thanks the sultan of Oman and the Omani authorities for their assistance, and all the people who contributed to this happy outcome", the French statement said.

Tribal sources said in July that the aid workers - two men and a woman from French non-governmental group Triangle Generation Humanitaire - were seized by al-Qaeda fighters in the Hadramawt town of Seyun, 600km east of Sanaa, the capital.

Their car was found on the road some 20km from Shibam, a city known as the "Manhattan of the Desert" because of its spectacular high-rise mud-brick buildings, a Yemeni security official said at the time.

On July 27, tribal sources said the kidnappers were from al-Qaeda and were demanding a ransom of $12 million.

The three appeared in an online video in September, saying their abductors' demands had not been met.

Local sources on Monday said that leaders of the Al-Awalaq tribe led negotiations with Fahd al-Qussa, a tribe member and a leader of al-Qaeda in the Arabian Peninsula (AQAP), which kidnapped the three.

Foreigners have frequently been kidnapped in Yemen by tribes who use the tactic to pressure the authorities into making concessions.

More than 200 foreigners have been kidnapped in Yemen over the past 15 years, with almost all of them later freed unharmed.

Source: Agencies