A senior Pakistani army officer and his friend were found shot dead on Thursday, two days after militants kidnapped them in the restive southwest province of Balochistan, security officials said.

The separatist insurgent Balochistan Liberation Army (BLA) released a statement saying it abducted and killed Lieutenant-Colonel Laeeq Baig Mirza, a rare attack on an officer of his rank in the region that borders Iran and Afghanistan.

Mirza was seized as he travelled back to the city of Quetta from Ziarat, a hill station, with his family and the friend on Tuesday night, a security official said.

"Around half a dozen militants blocked the Ziarat-Quetta Road some 22 to 25 km away from Ziarat (and) searched vehicles," the official told Reuters, asking not to be named as they were not authorised to talk to the media.

The gunmen took the officer and his friend, identified only as Umer, the official said. The men's bodies were found in different locations in the mountainous Hernai district on Thursday morning, another official said.

Military spokespeople did not respond to a request for comment.

The BLA and other separatist group have been waging an insurgency for years in Balochistan, a resource-rich region which has attracted substantial Chinese investment.

In April a suicide attack killed three Chinese teachers in Karachi, the capital of neighbouring Sindh province, drawing strong condemnation from Beijing. The BLA claimed responsibility.

In February, insurgents armed with bombs and guns attacked two Pakistani military bases in Balochistan, killing seven soldiers and losing 13 of their own men.