Two guards were killed and four others were kidnapped early on Saturday in a suspected Islamic State attack targeting Libya's Zella oilfield, a security source said.

The attackers struck at an entrance gate to the field, which lies near the town of Zella about 760 kilometres south-west of the capital, Tripoli. They killed the two guards before fleeing, the source and local residents asking not to be named told Reuters.

Islamic State claimed responsibility for the attack through its Aamaq news agency later on Saturday.