At least seven Pakistani paramilitary soldiers were killed and five others injured in a homemade bomb attack on a convoy in southwestern Balochistan province on Wednesday, media reports said.

Balochistan, which borders Afghanistan and Iran, has been witnessing a surge in violence in recent years as militant separatist groups stepped up their fight against Pakistani authorities, whom they accuse of exploiting the region's natural resources.

In a statement, the Pakistani military said "terrorists" from the Baloch Liberation Army (BLA) targeted a vehicle carrying security forces with a homemade bomb near the town of Mach in Kachhi district.

It said seven paramilitary troops were killed.

A senior local government official told AFP the vehicle that was hit was part of a convoy on its way to a security operation.

He said five others were wounded and were airlifted by helicopter to a military hospital in the provincial capital, Quetta.

The attack took place around noon in a mountainous coal mining region that has been hit almost regularly by attacks from separatist groups led by the BLA.

No one has yet claimed responsibility for the attack.

More than 200 people, mostly members of the security forces, have been killed since January 1 by armed groups in Balochistan and neighbouring Khyber-Pakhtunkhwa, according to an AFP tally.