An Iranian official says the toll for an explosion outside a mosque Thursday night has risen to 22 and may increase further.
Ali Mohammad Azad, governor general of Sistan-Baluchistan province has told state TV that "some 22 people were killed instantly" in the twin bombing in the southeastern city of Zahedan.
He estimates that the toll may increase further as many of the 160 injured are in serious condition.
Azad said Friday that "investigations on finding the responsible party will continue despite one group already claiming responsibility." He did not name the group.
The area is home to the Jundallah insurgency, a Sunni group that has killed scores in recent years.