At least six militants were killed in an overnight gun battle with security forces in western Pakistan's Balochistan province, an official said Tuesday.

Provincial government spokesman Jan Achakzai said "security forces successfully repulsed coordinated attacks" on at least three state facilities including a paramilitary HQ and a police station.

"Six terrorists were eliminated" during the assault in central Bolan district, he told AFP. Medical rescue teams reported 13 civilians were wounded, with two in critical condition.

The Balochistan Liberation Army (BLA) -- an armed separatist group -- claimed responsibility for the attack.

Islamabad has for decades battled ethnic separatist factions in Balochistan, Pakistan's largest but poorest province which is rich in natural resources.

Locals say they do not get their fair share of wealth from the oil and gas reserves, with the region consistently ranking at the bottom of Pakistan's human development indicators.

Rights groups say a military crackdown on ethnic Baloch citizens includes enforced disappearances and extrajudicial killings.

Tensions over militancy in the region flared this month when Islamabad hit BLA fighters sheltering in neighbouring Iran, after Tehran targeted anti-Iran militants sheltering in Pakistan.