A gun battle broke out overnight when armed men in the vehicles of Libya's new national army tried to take control of Tripoli's international airport from a powerful militia, the commander of the airport's security force said Sunday.

It was the latest in a series of clashes between the rival militias which, in the absence of a fully-functioning central government, have wielded real power on the streets in Libya since a revolt forced out former leader Muammar Gaddafi.

Mukhtar Al-Akhdar, commander of a militia unit from Zintan, south-west of Tripoli, which controls the international airport, told Reuters a convoy of vehicles approached a checkpoint about 3 km from the airport.

He said the armed men in the convoy said they had come to take over security, and a gunfight then broke out.

No one was killed. We have only two people injured on our side, Al-Akhdar said. These people were using national army vehicles. When we asked (acting army chief of staff Khalifa) Haftar about it, he said he did not know these people.

He said the row was defused after intervention from the head of the National Transitional Council (NTC) Mustafa Abdel Jalil, caretaker Prime Minister Abdurrahim El-Keib and Defense Minister Osama Al-Juwali.

NTC military spokesman Ahmed Bani did not comment on the details of the incident but said: There is no political or other problem. The problem is now sorted out.

BACKLASH AGAINST MILITIAS

Libya's central government is becoming slowly more assertive and signalling that it is time for the militias -- which emerged from the seven-month war to end Gaddafi's rule -- to hand over to the new national police and army.

Tripoli city council has given militias from other towns until December 20 to return home. The council chief said if they do not meet the deadline, all roads in the city will be blocked, except to defense and interior ministry vehicles.

Most militia leaders say publicly that they are ready to hand over to central institutions as soon as they receive the order to do so from the NTC.

But the national police and army are only just beginning to function. Some of the militias believe if they withdraw, that will leave a vacuum that will be filled by rival militias, in particular the powerful Islamists.

Tripoli international airport has already been a flashpoint for tensions. Late last month, armed men from Zintan briefly detained Abdel Hakim Belhadj, the Islamist leader of one of Tripoli's most powerful militias, as he tried to catch a flight.

Militia unit commander Al-Akhdar said his men were authorised to be at the airport. (We are here) because of orders from the NTC. They gave us a letter asking us to manage the airport and be in charge of its security, he said.

(Writing by Christian Lowe; Editing by Diana Abdallah)