Gunmen on a motorcycle assassinated an official of Iraq's biggest Shiite party Friday in the southern city of Basra, police said.

Sheik Salim al-Dirraji was gunned down in the Hayania district, which had been a stronghold of the Mahdi Army of anti-American cleric Muqtada al-Sadr until a security crackdown last spring.

Al-Dirraji was a local official of the Supreme Islamic Iraqi Council, the leading rival of al-Sadr's party within the Shiite community.