Militants stormed a paramilitary checkpoint in southwestern Pakistan on Saturday, killing seven troops, the latest in a string of attacks by separatist insurgents, police said.

The early-morning attack in the mountainous Kalat district, some 150 km south of Quetta, capital of the southwestern Balochistan province, continued for several hours, said police officer Habib-ur-Rehman.

Another 18 wounded paramilitary soldiers, some in critical condition, were admitted to local hospitals, he said.

Prime Minister Shehbaz Sharif condemned the attack.

Separatist militant group the Baloch Liberation Army (BLA) claimed that its fighters had attacked the checkpoint.

The group has stepped up its operations recently, claiming a suicide bombing last week that targeted Pakistani army troops at a railway station minutes before they were due to board a train to return home for vacations. It killed 27, including 19 soldiers, who were in civilian clothing.

The BLA and several other militant groups have been fighting for decades for a separate homeland to gain a greater share of the mineral and resource-rich Balochistan province, which borders Afghanistan and Iran. (Reuters)