Washington: The US military launched six drone strikes against Islamic State positions in Libya, months after militants were driven from safe havens there.

Officials announced the operation on Sunday, saying 17 militants had been killed and three vehicles destroyed when unmanned aircraft targeted a desert camp about 240 kms south-east of Sirte, a coastal city where ISIS fighters were defeated by US-backed Libyan forces last September.

An MQ-9 Reaper drone, some of which been used for air strikes in Libya in the past. Credit:AAP Image/University of NSW

Sirte served as an important logistics and planning hub for ISIS leaders, and it was considered a potential fallback if the terror group were to lose its de facto capital in Syria.

The attack on Friday comes as President Donald Trump seeks to further relax restrictions on attacking terrorists outside active war zones. Since assuming office in January, his administration has sought to roll back Obama-era regulations restricting strikes that put civilians at risk or where there is no "continued and imminent threat" to US personnel.