Iran has arrested a member of its military in connection with a gun attack on a military parade in the city of Ahvaz last month which killed 25 people, semi-official Fars News agency reported on Sunday.
An Iranian ethnic Arab opposition movement called the Ahvaz National Resistance, which seeks a separate state in oil-rich Khuzestan province, claimed responsibility for the attack.
Daesh terror organization also claimed responsibility. Neither group provided conclusive evidence to back up their claim.
"Eleven people were summoned and one was arrested, all of whom were military, and the case has been sent to Tehran," Gholam-Hossein Mohseni Ejei, spokesman for the judiciary, was cited as saying by Fars.
Ejei did not provide any further details.
Activists in the Ahvaz region have accused Iranian security forces of detaining their colleagues after the shooting attack last month.
Separately, Iran's Intelligence Minister Mahmoud Alavi said his ministry had helped to uncover and destroy "300 teams of militants", the Islamic Republic News Agency (IRNA) reported on Sunday.
Alavi did not give further details on the identities of the militants, nor did he indicate when the cells were uncovered.
