The US Africa Command said it "conducted a precision airstrike near Bani Walid, Libya, on August 28, killing one ISIS-Libya terrorist," referring to the Islamic State group.

The strike around 170 kilometres (105 miles) southeast of the capital Tripoli was coordinated with the UN-backed Government of National Accord, the US military said.

"At this time, we assess no civilians were injured or killed in this strike," the US African Command (AFRICOM) said in a statement.

A source within the Bani Walid security services said an "unidentified aircraft" targeted a pickup truck around four kilometres from the town.

The attack at 1:00 pm (1100 GMT) killed the driver, Walid Hariba, who the source said was a former IS leader in the city of Sirte.

In June 2015 IS jihadists overran the city, 600 kilometres east of Tripoli, and Hariba reportedly fled when they were ousted the following December.

A hospital official in Bani Walid said they had received Hariba's remains which were later released to the family, confirming his identity.

Despite being driven from Sirte by government forces and allied militias, IS remains active in Libya.

The US military regularly carries out air strikes in the country, and on June 6 said it had killed four members of an IS affiliate near Bani Walid.

Just days later AFRICOM said one "terrorist" had been killed in another such attack 80 kilometres southeast of Bani Walid, in a June 14 operation targeting Al-Qaeda in the Islamic Maghreb (AQIM).

In March US forces said they had killed Musa Abu Dawud, a high-ranking AQIM official, in an air strike in southern Libya.