Tripoli, July 15 (RHC)-- A rocket struck Libya's main international airport in the capital Tripoli, where fighting between rival armed groups was taking place. Witnesses said that the rocket hit the airport control tower late on Monday.

On Sunday, the airport was shut down for three days after deadly clashes erupted among rival militia groups who had tried to control the airport. Civil aviation authorities said the closure may be extended. The action comes as the United Nations has pulled its staff out of Libya.

In a statement released on Monday, the United Nations Support Mission in Libya said the closure of the airports and the deteriorating security in the key cities of Benghazi and Tripoli made it impossible to fulfill its work.

Nearly three years after the fall of Libyan leader Muammar Gaddafi, the North African country is still grappling with rising insecurity as the country has been witnessing numerous clashes between government forces and rival militia groups.

The former rebels refuse to lay down arms despite efforts by the central government to impose law and order. Thousands of angry Libyan demonstrators have frequently taken to the streets in different cities to protest against the lack of security across the country.