US and Iraqi forces kill 13

US and Iraqi forces killed at least 13 militiamen in clashes and air strikes overnight in Baghdad's Sadr City, but eased a blockade today that had trapped residents in the battle zone slum for two weeks.

Gunfire was still audible and some roads remained closed, but cars were allowed in and out of some entrances to the slum, home to 2 million poor Shi'ites and the power base of anti-American cleric Moqtada al-Sadr and his Mehdi Army militia.

Several hundred people have died in clashes between Sadr's followers and US and Iraqi forces since late March, when Shi'ite Prime Minister Nuri al-Maliki launched a crackdown against the militia in the southern city of Basra.

Sadr ordered his fighters off the streets on March 30, but the showdown has continued in his eastern Baghdad stronghold, turning Sadr City into a key front in the five-year-old war.

The Baghdad and Basra fighting has also thrust Iraq back onto centre stage of the US presidential election race.

Witnesses described the night's clashes as among the worst since Iraqi forces launched an offensive into the area a week ago.

A US military statement said at least 13 gunmen were killed in one overnight battle.

A US soldier was killed by an improvised explosive device in north-west Baghdad on Saturday.

Nearly two US soldiers per day have died in April, the highest toll since September.