Gunmen from a Libyan militia surrounded Tripoli's international airport on Monday to secure the release of one of their leaders whom they believed had been kidnapped and held there, a security official said.

The action by the Al-Awfea Brigade militia forced flights to be diverted to the capital's military airport, he said.

"The situation in the airport is very tense and tanks are surrounding the buildings. No one is allowed into the building," said the official, who declined to be named.

The incident is the latest in a series of events that highlighted the inability of the weak central government to assert its authority on a myriad of armed militias that have refused to give up their weapons after the popular revolution which ousted Muammar Gaddafi last August.

Last month, one person was killed and several wounded when militiamen protesting against the Libyan prime minister started shooting.

A Defence Ministry official said the militia at the airport had driven their armoured vehicles onto the runway and surrounded planes. "They are on the runway, in the car park, everywhere," he said. "There are no flights."     

A member of the Awfea Brigade told Reuters that they  believed their leader Colonel Abu Oegeila Al-Hebshi was being detained in the airport after being taken by the Tripoli Security Committee on Sunday night for reasons he did not know.

"We are protesting his kidnapping by coming to this airport," Anas Amara said. "We have one tank outside the airport and our cars are surrounding the airplanes so they don't fly."     

The militia is from the town of Tarhouna, 80 km (50 miles) southeast of Tripoli. An airport customs official said flights were cancelled and incoming planes were diverted to Tripoli's Mitiga Airport.  
The ruling National Transitional Council spokesman, Mohammed al-Harizy, said Hebshi was taken by unknown armed rebels while travelling between Tarhouna and Tripoli last night.

Austrian Airlines cancelled its flight to Vienna on Monday, a company staffer said. "Passengers due to fly out have gone home and the crew have been taken to a hotel. We are waiting to see what happens," the staffer, who declined to be named, said.

Several international airlines have resumed flights to Tripoli although security concerns have lingered since the end of the conflict last year. - Reuters