Saudi Arabia's ruling family committed a crime by executing Shia cleric Nimr al-Nimr, the leader of a powerful Iranian-backed Iraqi militia said on Saturday, according to al-Ahd TV.

"The execution of Sheikh al-Nimr is a crime that is added to the criminal record of Al Saud," Kataib Hezbollah's leader Abu Mahdi al-Mohandes said.

Al-Ahd is owned by another Iranian backed group, Asaib Ahl al-Haq.