A militia has shelled Tripoli airport, destroying 90% of planes parked there, a Libyan government spokesman said.

The heavy fighting between armed groups has prompted the United Nations to pull its staff out of the country.

At least 15 people have been killed in clashes in Tripoli and the eastern city of Benghazi since Sunday.

A Libyan official has also said several Grad rockets hit the Tripoli International Airport yesterday, damaging the control tower.

Government spokesman Ahmed Lamine said 90% of the planes parked at the airport were destroyed.

"The government has studied the possibility to bring international forces to enhance security," he told reporters.

Three years after the fall of Muammar Gaddafi, Libya has slipped deeper into chaos with its weak government and new army unable to control brigades of former rebel fighters and militias who often battle for political and economic power.

The UN mission in Libya said the closure of Tripoli airport and the deteriorating security situation made it impossible for it to operate.

Elsewhere, Misrata city airport was also closed yesterday and Benghazi airport has been closed since May.

That leaves only two small airports in the south and a land route to Tunisia as the country's only gateways to the outside world, a flashback to the 1990s when Libya was under UN sanctions.