BAGHDAD, Aug. 10 (Xinhuanet) -- Fierce clashes between US troops and Shiite militiamen loyal to Iraq's radical cleric Moqtada al-Sadr continued for a sixth straight day on Tuesday.

    Explosions and gunfire were heard in the heart of Najaf and its ancient vast cemetery as US aircraft flew overhead and US tanks pounded Sadr's Mehdi Army positions, witnesses said.

    The clashes in Najaf erupted just after 8:00 a.m.(0400 GMT) Tuesday following a night of intermittent gunfire.

    In Baghdad's mainly Shiite suburb, Sadr City, the clashes raged for three and a half hours early Tuesday when a US patrol came under several attacks as it drove through the centre of the suburb,a US military spokesman said.

    According to the spokesman, the Sadr militiamen attacked the "large number" of troops with rocket-propelled grenade, small arms fire and makeshift bombs from 4:30 a.m. (0030 GMT) to 8:00 a.m.(0400 GMT).

    There had been Iraqi casualties, but no injuries to US soldiers or damage to any equipment, the spokesman added.

    A curfew had been imposed Monday until 8:00 a.m. (0400 GMT) Tuesday after fierce fighting between Sadr's followers and US forces. Enditem