The state-run IRNA agency said the clashes took place after Revolutionary Guards ground forces descended on the area, 17km from the Turkish border, in pursuit of the rebels.

"The Revolutionary Guards besieged these elements and started neutralising them. In this operation at least 17 mercenary anti-revolution elements were killed and some were injured," the report quoted a Guards statement as saying.

It said that the commander of the ground force carrying out the operation had an "accident due to bad weather" while flying by helicopter with eight others to check on the area.

The report did not say if there were casualties in the accident.

The Guards were continuing "to fully clean-up the region of anti-revolutionary elements," the report said, without giving further details about the rebels.

Iran's northwestern West Azarbaijan province, which has borders with Turkey and restive Iraq, is home to a minority of ethnic Kurds.

The area has already been the scene of regular armed clashes between Iranian border guards and Kurdish militant parties, in particular Pejak -- a group linked to Turkey's outlawed Kurdistan Workers' Party (PKK).