Kamal Hadianfar said most had been based "in provinces near border areas," without specifying where.
Turkey 'astonished' by Iranian charges of Islamic State support
Shia 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.
Iran's Khamenei holds similar beliefs as Islamic State: US Senator
Iran has also sent officers to help in the fight against IS militants in Syria.
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