Military officials Saturday said forces seized the Hayaniya neighborhood, a stronghold of the Mahdi Army militia loyal to radical Shi'ite cleric Moqtada al-Sadr.

A British military spokesman, Major Tom Holloway, said British artillery and U.S. warplanes launched shells and dropped bombs in an unoccupied area, west of the neighborhood, in support of Iraqi troops. He said the intent was to show militants the firepower available to the Iraqi Army.

A spokesman for Iraq's Interior Ministry, Major General Abdel Karim Khalaf, said the area is now calm.

No casualty figures were immediately available.

Elsewhere in Baghdad's Sadr City, reports say at least 12 people were killed in heavy fighting during pre-dawn clashes between Shi'ite militiamen and U.S.-backed Iraqi forces.

In a bid to stem the violence in the area, U.S. forces are building a massive concrete wall along a road, Al-Quds Street, that cuts through Sadr City.

And at least one militant was killed when Iraqi troops and members of the Mahdi Army clashed in the southern city of Nasiriyah.

Some information for this report was provided by AFP and Reuters.