The four were identified as members of Komala -- a banned leftist Kurdish group -- who had killed three policemen last December in the province that borders Iraq and Turkey, the statement said.

"They were ambushed and killed Sunday morning in an area near the town of Sardasht," it said, adding that several weapons and grenades had been seized.

Western Iran, which has a sizeable Kurdish population, has seen deadly clashes in recent years between Iranian security forces and Kurdish rebels operating from bases in neighbouring Iraq.