Air strikes on a Baghdad militia stronghold and in the southern Iraqi city of Basra killed 12 gunmen overnight, US and British military said on Friday.

US soldiers operating a drone plane over the eastern Baghdad Shi'ite slum of Sadr City late on Thursday fired a Hellfire missile at a group of men carrying rocket-propelled grenade launchers, killing six, the US military said.

In Basra, Iraq's second largest city, British forces launched an air strike against fighters they said engaged Iraqi ground troops, killing six and wounding one, the British military said.

"We had our eyes on an enemy mortar team which was firing on Iraqi armed forces on the ground," said British Major Tom Holloway. "The mortar team had been engaging Iraqi ground forces."

Basra has been relatively quiet since Shi'ite cleric Moqtada Al Sadr called his Mehdi Army militia off the streets of the city nearly two weeks ago.

Iraqi Prime Minister Nuri al-Maliki launched a crackdown on militias in Basra in late March, sparking a new wave of violence in southern Iraq and Baghdad.-Reuters