Iraqi Shia cleric Moqtada al-Sadr has threatened to stage nationwide civil disobedience if attacks against his supports are not halted.

"If the government does not respect these demands, the second step will be general civil disobedience in Baghdad and the Iraqi provinces," Sadr's representative Hazam al-Aaraji quoted him as saying in a statement on Tuesday.

Police launched a major crackdown on Mahdi Army forces in the southern city of Basra on Tuesday. At least four people were killed and 18 wounded in the clashes, said police Major Abbas Youssef.

Fighting erupted soon after security forces entered the al-Tamiyah neighborhood, a bastion of Sadr's Mahdi Army forces, at around 5:00 am (0200 GMT), AFP reported

In the wake of the fighting police also imposed curfews in three other southern cities -- Kut, Samawa and Nasiriyah -- as precautionary measures.

SB/RE