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BASRA, Iraq, March 24 (Reuters) - Iraqi authorities on Monday imposed a night-time curfew on the movement of people and vehicles in the southern province of Basra until further notice due to clashes between police and members of Mehdi Army militia.

"To impose the law and chase the criminals ... we have decided to impose a curfew in the whole of Basra starting from tonight at 10 p.m. until 6 a.m. and everyday after until further notice," said Lieutenant-General Mohan al-Furaiji.

Authorities said they would also temporarily close access to Basra, 550 km (340 miles) southeast of Baghdad, from neighbouring provinces during the evening hours starting from Wednesday and lasting until Friday.

Schools and universities will also not hold classes on Wednesday and Thursday.

Earlier on Monday, Iraqi Shi'ite cleric Moqtada al-Sadr's Mehdi Army militia ordered shops to close in some Baghdad neighbourhoods in what they said was the start of a "civil disobedience campaign."

The militia has kept a low profile since Sadr called a ceasefire last August and extended it last month.

But gunbattles in Baghdad and the southern city of Kut last week have raised fears that it may be unravelling at a time when the U.S. military is withdrawing 20,000 troops. (Reporting by Aref Mohammed; Writing by Randy Fabi; Editing by Jon Boyle)

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