At least 40 soldiers were killed by suicide attacks on Thursday in Libya’s second city of Benghazi, as militias fought for control of a key airbase.

Four suicide attacks targeted the Benina base and the soldiers who are supporting former General Khalifa Hifter.

The Shura Council of Benghazi Revolutionaries said it carried out the attack, alongside the Libya Shield brigade and Ansar al-Sharia.

Hifter’s forces have been fighting Islamist factions since May, attacking rival militias in Benghazi and briefly taking over the Parliament building in Tripoli. They have been bolstered by defections from the Libyan Army and support of tribal units.

Since the overthrow of Muammar Qaddafi in October 2011, Libya’s central Government has been unable to establish a national force to subsume or defeat the militias, and Tripoli now finds itself dependent on some of those militias to maintain “order”.

The country has also been racked by economic turmoil, including strikes which have paralyzed much of its oil industry.