Iran's intelligence ministry has arrested three people suspected of being behind a bomb attack on a military parade in 2010, media reports said Sunday.
The explosion in the ethnically Kurdish northwestern town of Mahabad in West Azerbaijan province killed 12 spectators and wounded 81 others.
Western Iran, which has a sizable Kurdish population, has seen deadly clashes in recent years between security forces and rebel groups operating from bases in neighbouring Iraq.
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"Intelligence officers identified a terrorist team in the city of Mahabad and three members of the group were arrested," the official IRNA news agency cited an intelligence ministry statement as saying.
The report added that the detainees confessed to being affiliated to the Iranian Kurdish rebel group known as Komala.
A week after the 2010 attack, the Revolutionary Guards said its forces had killed 30 perpetrators of the Mahabad bombing, apparently in a cross-border raid into Iraq.