U.S. forces in Iraq say seven American soldiers have been killed and more than two dozen wounded in clashes with Shi'ite Muslim militiamen in Baghdad.

In a statement, the U.S. military said soldiers fought off militiamen loyal to radical Muslim Shi'ite cleric Moqtada al-Sadr. [The statement says the militiamen were trying to take over police stations and other public buildings in Sadr City, a mostly Shi'ite neighborhood of Baghdad.]

The latest report comes hours after at least 20 Iraqis and two coalition soldiers were killed near the holy city of Najaf, in southern Iraq.

Deadly clashes between armed demonstrators and coalition troops broke out after angry supporters of radical Shi'ite cleric Moqtada al-Sadr took to the streets in several cities across Iraq.

The protesters were calling for the release of a top aide to the cleric, Mustafa al-Yacoubi, who coalition officials arrested Saturday in connection with the killing of another Shi'ite cleric last year. Many of the demonstrators were also protesting the U.S. decision to temporarily close down a newspaper headed by Moqtada al-Sadr, which coalition officials said was "inciting violence."

Coalition administrator Paul Bremer said freedom of expression is welcome in Iraq, but must be exercised peacefully. "This morning a group of people in Najaf have crossed the line and they have resorted to violence. This will not be tolerated," he said.

Kurdish leader Massoud Barzani, who holds the rotating presidency of the interim Iraqi Governing Council this month, also condemned the violence, saying Iraqis should express themselves by peaceful and democratic means.

According to a statement issued from al-Sadr's office, the influential Shiite leader, who is known for harshly criticizing the U.S.-led coalition, called for his followers to stop demonstrating and "terrorize your enemy." Elsewhere in Iraq, British troops clashed with al-Sadr supporters in the southeastern Iraqi town of Amara. No casualties were reported.

In the northern city of Kirkuk, a suicide bomber blew himself up in a car near another Shiite demonstration. At least two U.S. soldiers and five Iraqis were wounded in the blast.

Mr. Bremer also announced the appointment of a new Iraqi defense minister and chief of intelligence. He said the new Defense Ministry and intelligence service will play an important role in Iraq's security.

Ali Allawi, a U.S. and British-educated expert on Middle East affairs and longtime opponent of Saddam Hussein's Baath party, will become the new defense chief. The new leader of the Iraqi National Intelligence Service is Mohammed al-Shehwani.

Meanwhile, a U.N. team headed by special envoy, Lakhdar Brahimi, arrived in Iraq for talks with leaders over the political future of the country.