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ANKARA, Dec 7 (Reuters) - Iran's cyber police chief said on Monday officers had arrested 53 people for running websites supporting the Islamic State militant group (IS), Tasnim news agency reported.

Shi'ite Muslim power Iran said last month it had broken up a cell recruiting fighters for the hardline Sunni Muslim group in Kermanshah, a western province close to the Iraqi border.

The area has a large Sunni Kurdish population that has risen up against Tehran in the past

The cyber police chief, Kamal Hadianfar, said most of those arrested had been based "in provinces near border areas", without specifying where.

IS has seized swathes of territory in both neighbouring Iraq and also in Syria, where Iran has sent security officers to help President Bashar al-Assad's forces battle the militants.

Iran's semi-official Students News Agency ISNA said the arrests had taken place in the past 20 months and that some of those arrested had been released.

"Among those arrested, the cases of those who confessed ... were referred to the judiciary while some whose involvement were based on their unawareness (of what they were doing were released)," ISNA quoted Hadianfar as saying.

No further details were immediately available.

(Writing by Parisa Hafezi; Editing by Gareth Jones) ((parisa.hafezi@thomsonreuters.com; +90 532 176 3452; Reuters Messaging: parisa.hafezi@thomsonreuters.com))