Libya ordered the closure of its borders with four of its neighbours on Sunday, as it declared the desert south of its territory a closed military zone in the face of mounting unrest, state media reported.

The National Assembly ordered the "temporary closure of the land borders with Chad, Niger, Sudan and Algeria pending new regulations" on the circulation of people and goods, said a decree carried by the official LANA news agency.

"The provinces of Ghadames, Ghat, Obari, Al-Shati, Sebha, Murzuq and Kufra are considered as closed military zones to be ruled under emergency law," the decree stipulated.

An assembly member who represents the city of Sebha, much the largest in the south, said the border closure was a "temporary measure" that would last only "until security has been restored."

She said there had been an "increase in the flow of illegal immigrants in the expectation of eventual international military action in Mali" against Al-Qaeda-linked rebels, who have seized much of the north of the country.

She said the move was also in response to an "upsurge in violence and drug trafficking, and the presence of armed groups that act with complete impunity."