Justice Minister Salah al-Marghani said there were 20 to 30 armed men in military fatigues who arrived in trucks with anti-aircraft guns mounted on them. The government official tried to talk to them before he had to flee.

The attack came a day after militants killed a pro-government militiaman in an area further east, and less than a week after a car bomb exploded outside the French Embassy in Tripoli, where three were wounded and the building was partially set on fire.

A suspected car bomb hit the French embassy in Tripoli, Libya, on Tuesday, in the first attack on a foreign mission since militants stormed the US consulate in Benghazi in September.

"Gaddafi's wife, two sons and a daughter, as well as their children have been in Oman since October last year," an official told Reuters.