At least four people have been killed in a double suicide bombing at an army base in the eastern Libyan city of Benghazi, a security source has told Reuters news agency.

Militias and security forces have been clashing regularly in the city, but suicide attacks have been rare during the turmoil that has followed the 2011 overthrow of longtime ruler Muammar Gaddafi.

A medical official said the blasts killed four people, not including the two attackers themselves, as well as an "unknown number of wounded".



The attack hit just as the men were breaking the fast for the Muslim holy month of Ramadan, the military source added, saying that a bomber on a lorry forced his way onto the base before detonating the vehicle.



This was followed by a second attacker in a car, the military official said. No group has so far claimed responsibility.

Tuesday's blast occured as a day after fighters attacked an army base in the city, triggering fierce clashes involving helicopters and jets that killed at least seven people and wounded 40 others.

The violence came as armed groups engaged in a more than one-week long battle for control over the capital, Tripoli's main international airport.

At least three people have been killed as armed groups have been fighting for the control of the country's largest airport.