Iraq announced on Monday that a high-level security officer during the rule of Saddam Hussein has been hanged for his involvement in the 1980 killing of a prominent Shiite cleric.

The National Security Service said that Saadoun Sabri al-Qaisi, who held the rank of major general under Saddam and was arrested last year, was convicted of “grave crimes against humanity,” including the killing of prominent Iraqi Shiite cleric Mohammed Baqir al-Sadr, members of the al-Hakim family, and other civilians.

The agency did not say when al-Qaisi was executed.

Al-Sadr was a leading critic of Iraq's secular Baathist government and Saddam, his opposition intensifying following the 1979 Islamic Revolution in Iran, which heightened Saddam’s fears of a Shiite-led uprising in Iraq.

In 1980, as the government moved against Shiite activists, al-Sadr and his sister Bint al-Huda — a religious scholar and activist who spoke out against government oppression — were arrested. Reports indicate they were tortured before being executed by hanging on April 8, 1980.

The execution sparked widespread outrage at the time and remains a symbol of repression under Saddam's rule.

Since the 2003 U.S.-led invasion of Iraq, authorities have pursued former officials accused of crimes against humanity and abuses against political and religious opponents.