The car bomb in Baghdad, meanwhile, struck a mostly Shiite district to the east that attracts crowds of shoppers and laborers looking for work.

In another part of eastern Baghdad, a suicide bomber exploded in a minibus, killing three people and injuring 19, police said.

Special coverage: Escalating Violence in Iraq Related readings:  7 killed in raid on Iraq police station 6 US troops die in bloody Iraq weekend Top Shiite cleric balks at plan for Iraq Gunmen slay Iraqi intelligence officer US death toll nears 3,000 in Iraq US Marines charged in 24 Iraqi killings

Another suicide bomber killed two policemen at a checkpoint at a university entrance in Ramadi, capital of Anbar province, a stronghold of the Sunni-dominated insurgency.

The deaths came a day after Iraq's interior minister said attacks targeting police had killed some 12,000 officers since the 2003 fall of Saddam Hussein.

The US command announced that an American soldier and a Marine had died Sunday from combat wounds suffered in Anbar province.

Another soldier died and two were wounded Monday when a roadside bomb exploded near a US military vehicle in southern Baghdad, the military said.

At least 2,972 American troops have died since the beginning of the Iraq war in March 2003, according to an Associated Press count. The Sept. 11, 2001 attacks claimed 2,973 victims in New York, Washington and Pennsylvania.

Christians attended Christmas services in Baghdad and northern Iraq, home to most of Iraq's 800,000 Christians. Some in Baghdad stayed home, however, fearing violence.

Christians are on the fringes of the conflict, which mostly involves Shiite Muslims and Sunni Arabs ¡ª but they have been targeted by Islamic militants.

"I hope next year will bring good things and unite all Iraqis because there is no difference between Christians and Muslims," said Abu Fadi, a worshipper who does not use his Christian name because he fears for his safety. "May God bring relief from this."

In another sign of escalating diplomatic tensions between the US and Iran, the White House said Monday that US troops in Iraq detained at least two Iranians and released two others who had diplomatic immunity.

US officials have charged that Iran provides training and other aid to Shiite militias in Iraq ¡ª including the equipment used to build roadside bombs. The Tehran regime says it only has political and religious links with Iraqi Shiites.

But Iran is believed to be expanding its shadowy role in Iraq, partly to counter US influence in the region.

In Baghdad, a spokesman for Iraqi President Jalal Talabani confirmed that US troops had detained two Iranians who were in Iraq at his invitation. "The president is unhappy about it," said Hiwa Osman, Talabani's media adviser.

He gave no further details, and the US military said it had no comment.

"We suspect this event validates our claims about Iranian meddling, but we want to finish our investigation of the detained Iranians before characterizing their activities," White House spokesman Alex Conant said Monday. "We will be better able to explain what this means about the larger picture after we finish our investigation."

He said that a routine raid on suspected insurgents netted the Iranians. Two had diplomatic immunity and were released to the Iraqi government, which then released them to Iran, Conant said.

1

2