Iraq has released an Iran-aligned militia commander arrested in May on terrorism-related charges after authorities found insufficient evidence against him, in the latest blow to government attempts to rein in armed groups.

Security forces arrested Qasim Muslih, an Iran-aligned paramilitary leader who operates mostly in Iraq's western Anbar province and is from Kerbala, on May 26.

The military had said the charges were terrorism-related but did not give details.

Prime Minister Mustafa al-Kadhimi has placed himself publicly in opposition to Iran-backed militias and parties, and Muslih's arrest was a major attempt to rein in their power.

Two high-profile moves against Iran-backed factions - the arrest of Muslih in May and the detention in June 2020 of fighters allegedly involved in rocket fire against U.S. targets - have each resulted in no prosecutions and all those arrested being released.