American and Iraqi forces have killed more than 20 insurgents during raids in areas used by militants to stage attacks in Baghdad, the U.S. military said Sunday.

In violence Sunday, a roadside bomb hit a U.S. military convoy in central Tikrit, the hometown of Saddam Hussein, said police Maj. Ahmed Awad said. He said the blast set a Humvee on fire and caused U.S. casualties, but the U.S. command could not immediately confirm that.

The U.S. military said the raids have taken place in and around Youssifiyah, a town about 12 miles south of Baghdad, where an American helicopter apparently was shot down by insurgents nearly a month ago, killing the two soldiers aboard.

In the latest operations Saturday, U.S. and Iraqi forces attacked buildings used by foreign insurgent groups such as al-Qaida in Iraq, capturing seven militants and detaining more than 50 suspects, the U.S. command said.

Insurgents have been using the Youssifiyah region as a staging ground for suicide attacks Baghdad, the command said. Several of the 20 insurgents killed in the last few weeks were wearing suicide vests, it said.

Twelve of the militants, at least five of them foreign, were killed Tuesday when U.S. troops backed by a helicopter and jets struck a suspected safe house in Youssifiyah, the U.S. military said.

Mujahedeen Shura Council, purportedly a new umbrella organization that includes al-Qaida in Iraq and smaller insurgent groups, claimed responsibility for April 1 attack on the Apache helicopter. The U.S command said at the time it believed the chopper was shot down.

The U.S. military did not say whether those killed in the latest raids were believed to have been involved in the helicopter crash. The area is part of the infamous "triangle of death" and the scene of numerous ambushes against U.S. and Iraqi troops, foreigners and Shiite civilians.

On Saturday, a roadside bomb killed a U.S. soldier southwest of Baghdad, raising to 70 the number of American service members killed in April — the highest monthly figure since November, when 84 died. The U.S. military would not give the precise location of Saturday's attack or say whether it was related to the coalition raids.

On Sunday, two roadside bombs targeting separate Iraqi police patrols exploded within a half hour of each other in two areas of western Baghdad, wounding two policemen and a civilian driving nearby, police said.

In the Sadr City section of Baghdad, a bomb exploded aboard a minibus near a gas station, wounding three Iraqi civilians, said police Lt. Thair Mahmoud.

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