Four people were killed in clashes among rival Shiite Muslim militants in the southern Iraqi city of Basra, which took place overnight and into Thursday morning, local security officials said.

The clashes occurred in the center of Basra, Iraq's main oil-producing hub. 

The skirmishes were the latest violence to hit the country in a political crisis that pits followers of the powerful Shiite cleric Moqtada al-Sadr against mostly Iran-aligned parties and paramilitary groups.