At least 11 people were beheaded Wednesday in an attack on a checkpoint controlled by Libyan military strongman Khalifa Haftar south of Tripoli, a spokesman for his forces said.

"At least nine soldiers were beheaded... in addition to two civilians killed in the same way" at the checkpoint about 500 kilometres (300 miles) south of Tripoli, Colonel Ahmad al-Mesmari said, blaming the Islamic State group for the attack.