IRNA on Saturday quoted Governor Noorollah Arjmoandi saying that the attackers drove up in cars and fired RPGs at the main prison in Ilam province, western Iran.
The semi-official Mehr news agency, however, quoted prison official Ali Reza Babaei as saying that the explosion was caused by a bomb, injuring 19 people, three of them prison guards.
Mehr said the two prisoners who escaped were convicted murderers and one of them had been scheduled to be hanged.
