The armed clash took place late last night in Kohlu and Dera Bugti districts, a government official said.
"We have received information about an armed clash but the exact number of casualties is not yet known but we have been told at least 22 insurgents have been killed from both groups," he said.
Initial reports confirmed that both the groups had used heavy and sophisticated weapons against each other leading to the heavy casualties on both sides, the official said.
The Kohlu and Dera Bugti districts have a heavy presence of separatists who regularly target vital national installations and security forces in the area.