In violence Sunday, a roadside bomb hit a US 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 US casualties, but the US command could not immediately confirm that.

The US military said the raids have taken place in and around Youssifiyah, a town about 20km 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, US and Iraqi forces attacked buildings used by foreign insurgent groups such as al-Qaeda in Iraq, capturing seven militants and detaining more than 50 suspects, the US 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 US troops backed by a helicopter and jets struck a suspected safe house in Youssifiyah, the US military said.