At least 20 killed as Shia militants clash with US and Iraqi forces in Sadr City

Shia militants fought US and Iraqi forces around Baghdad's Shia district of Sadr City yesterday, despite a call for calm by the anti-American cleric Muqtada al-Sadr following the assassination of one of his top aides. At least 13 Shia militants and seven civilians died in the clashes between US and government troops and Mr Sadr's Mehdi Army militia. One US soldier was killed by a roadside bomb.

Mr Sadr blamed the Americans and their Iraqi allies for the death on Friday of Riyadh al-Nouri, director of his office in the Shia holy city of Najaf. Gunmen ambushed him as he returned home from prayers. A curfew was declared to prevent a violent backlash by Sadrists, but was lifted yesterday.

Government troops supported by the US military have been fighting for nearly two weeks to seal off Sadr City, the principal stronghold of the Mehdi Army in the capital, after militants there fired rockets and mortars at the US-protected Green Zone.

According to officials in Sadr City, Sadrist militiamen received instructions from the movement's headquarters in Najaf on Friday to avoid confrontations with Iraqi and US forces, and not to fire on them unless they attempted to penetrate deep into Sadr City. The Sadr officials, who spoke on condition of anonymity, said the movement was concerned that clashes with security forces were turning into a war of attrition which rival Shia groups were exploiting to weaken the Sadrists.

The conflict in Sadr City is part of a major power struggle within the Shia community ahead of provincial elections due this autumn. Meanwhile, in Basra, Iraq's second largest city, the Iraqi army said it was conducting a sweep of the city's Qibla district, looking for illegal weapons, ammunition and wanted criminals.