BAGHDAD (AFP) - - Fierce clashes between Shiite militiamen and US and Iraqi forces in eastern Baghdad killed at least 38 people, including 22 who died when a US tank fired on attackers, the American military said Monday.

Others died when troops responded after they were attacked with small arms fire and rocket-propelled grenades in Sadr City, the Baghdad bastion of the Mahdi Army militia of radical Shiite cleric Moqtada al-Sadr, statements issued Monday said.

The major attack on the checkpoint was carried out by "a large group of criminals engaging with small-arms fire" at around 6.35 pm (1535 GMT) on Sunday.

"US soldiers used 120 mm fire from M1A12 Abrams tanks and small arms fire to kill the 22 criminals, forcing remaining enemy forces present to retreat," the military said.

"The criminals' small arms fire was ineffective and there were no US soldier or Iraqi security force casualties in the attack."

The latest deaths bring to at least 439 the number of militiamen and civilians killed in a month of clashes in Sadr City, where violence erupted after Prime Minister Nuri al-Maliki ordered a countrywide crackdown on militias, starting in the southern oil city of Basra.

At least 15 US soldiers have died in Baghdad since the clashes began.