A Libyan security official says a suicide car bomber has targeted a checkpoint manned by troops loyal to a rogue Libyan former general, Khalifa Haftar outside the eastern city of Benghazi, wounding three people.

The official says the bomber detonated his explosives-laden vehicle on Wednesday night, killing himself and wounding three of Haftar's fighters.

The official spoke on condition of anonymity because he was not authorised to talk to the media.

Haftar is leading an offensive against the Islamic militias and Islamists that dominate Libya's politics. His troops, along with their allies, have bombed militia camps in and around Benghazi in recent weeks.

The fighting has escalated the crisis in Libya, which has been in turmoil since the 2011 civil war and the downfall of longtime dictator Muammar Gaddafi.