Iranian authorities have arrested hundreds of people and executed dozens in a wave of repression following the 12-day war with Israel, activists say, accusing the Islamic republic of using fear to compensate for weaknesses revealed by the conflict.

Campaigners have been detained on the street or at home, executions expedited, prisoners transferred to unknown locations and minorities also targeted, according to rights groups.

Six men have been hanged on charges of spying for Israel since the start of the conflict, dozens more on other charges and more than 1,000 arrested during or after the conflict on charges related to the war, according to Iran Human Rights, a Norway-based NGO.