"What happened in the Evin prison is a crime which was committed by hostile agents," Ejei said, as quoted by the IRNA news agency.
Iran's chief justice noted that these agents served as an "operational staff" during the fire at the prison and helped Israeli, British and US "elements" organize civil unrest in the country.
Some inmates tried to escape from the prison but were caught, IRNA said, adding that on Sunday morning, the situation in the prison stabilized.
On Saturday night, a fire broke out in the prison's workshop as a result of conflict between several inmates. Though the blaze was extinguished several hours later, it left eight people dead and more than 60 injured.