FACTBOX-Security developments in Iraq, March 26

(Reuters) - Following are security developments in Iraq at 8:30 p.m. British time on Wednesday.

BASRA - Fighting between Iraqi security forces and the Mehdi Army militia continued in Basra. A health official said 40 people had been killed and 200 wounded since a major Iraqi military operation began on Tuesday.

BAGHDAD - Twelve people have been killed and 77 wounded in clashes between Iraqi security forces and the Mehdi Army in Baghdad's Sadr City district since Tuesday, said Ali Bustan, general director of the health office for eastern Baghdad.

HILLA - U.S. helicopters struck the town of Hilla in support of Iraqi police battling militia members. Four Iraqi security sources spoke of large numbers of casualties in the air strike. U.S. forces confirmed the strike but said they did not believe large numbers of people had died.

BAGHDAD - Mortar attacks killed five and wounded 20 in Baghdad's Karrada district, police said.

BAGHDAD - Two people were killed in Shaab district and one person in Kadhimiya district from fighting between Iraqi security forces and the Mehdi Army.

BAGHDAD - Mortar attacks killed four people and wounded 12 in Baghdad's south-western district of Risala.

BAGHDAD - Three U.S. citizens working for the U.S. government in Baghdad were seriously wounded in a mortar attack in the Green Zone, the diplomatic and government compound, a U.S. embassy spokeswoman said.

KUT - Eighteen people were killed, including a baby girl, and dozens wounded in fighting between Mehdi Army members and Iraqi security forces in Kut, 175 km (105 miles) southeast of Baghdad, police and hospital sources said. Police said the militia had taken control of seven neighbourhoods.