ANKARA (Reuters) - Police in Iran killed four Islamic State in Iraq and Syria (ISIS) suspects, two of whom were foreigners, in the southern province of Hormuzgan and seized explosives, guns and the group's flag, an Iranian news agency said on Monday (June 12).

A major security operation is underway after 17 people were killed last Wednesday (June 7) in suicide bombings and gun attacks in Teheran, the first to be claimed by the hardline Sunni Islamist group inside Iran, a Shi'ite power.

"Police forces clashed with the four men and killed them in a mountainous area in southern Iran," the semi-official Tasnim news agency quoted a local police chief as saying.

Two of those killed were not Iranian, he said.

Guns, ammunition, explosives and the flag of ISIS were seized during the operation, Tasnim reported, citing the police chief.

Hormuzgan, which borders Pakistan and Afghanistan, is home to a Sunni minority and has seen previous clashes between security forces and Sunni insurgent groups.

The authorities say Iranian security forces killed the mastermind of the attacks on Saturday (June 10) and that more than 50 suspects have been arrested around the country.

Iran accuses Saudi Arabia of funding hardline Sunni militants, including ISIS, and in the wake of last week's attack pointed the finger at its regional rival. Riyadh has denied involvement in the attacks.