The Iranian military has killed 17 rebels in the north-west of the country, state media have reported.
Iran's Revolutionary Guards are an ideological, well-armed force
A unit of Revolutionary Guards attacked the rebels in a remote area near the Turkish border, IRNA news agency said.
A military helicopter involved in the operation crashed in bad weather, killing a Guards commander on board, Fars news agency reported.
There have been previous clashes in the area between Iranian security forces and militants linked to Kurdish groups.
"The Revolutionary Guards besieged these elements and started neutralising them," IRNA quoted a Guards commander as saying.
"In this operation at least 17 mercenary anti-revolution elements were killed and some were injured."
Fars said that a Revolutionary Guards commander named Saeed Ghahari was killed in the helicopter crash, in West Azerbaijan province.
IRNA blamed the crash on bad weather.
West Azerbaijan province borders both Turkey and Iraq.
The head of Iran's Revolutionary Guards, Yayha Rahim, blamed foreign countries for trying to stir up unrest in Iran's border regions.
"Enemies headed by the United States, Britain and the Zionist regime [Israel] who have had their goals defeated in the region are seeking insecurity in some border areas," Mehr news agency quoted Mr Rahim as saying.
The past two years have seen a rise in violent incidents in a number of regions inhabited by Iran's minorities, amid complaints of government oppression, discrimination or political or economic neglect, says the BBC's regional analyst Pam O'Toole.
A bomb attack on 14 February in south-east Iran killed 13 Revolutionary Guards in the majority Sunni city of Zahedan.
Last year also saw angry demonstrations by ethnic Azeris in Azerbaijan province, while in 2005 there was a wave of protests in Kurdestan province.