"Three chiefs of the counter-revolutionary group Pejak who have been given a mission by the enemies to create trouble were killed on Monday," Commander Hassan Rastegar-Panah told the official IRNA news agency.

He said that numerous wounded Pejak fighters were still hiding in the region and were being pursued by Iranian forces.

"Documents found show that the objective of the rebels was to create insecurity in the area," he added.

The Revolutionary Guards said on Saturday that they had killed 17 rebels in the area but later added that 14 Iranian military personnel were also killed in a helicopter accident during the operation.

Pejak, a separatist Kurdish rebel group, claimed in a statement sent from northern Iraq that it had shot down an Iranian helicopter.

The group, linked to Turkey's outlawed Kurdistan Workers' Party (PKK), also claimed to have fought an hour-long battle with Iranian troops and to have killed 20 soldiers, including senior officers.

Iran's northwestern West Azerbaijan province, which borders Turkey and Iraq, is the scene of frequent armed clashes between Iranian border guards and Kurdish rebel groups, Pejak in particular.

The authorities have often accused the United States and Britain of seeking to stir unrest amongst ethnic minorities in areas close to the Turkish, Iraqi and Pakistani borders.