Baghdad, Iraq ? An armed confrontation between two Iraqi army units left one soldier and one civilian dead Friday, raising questions about the U.S.-trained force’s ability to maintain control at a time when sectarian and ethnic tensions are running high.

The incident near Duluiyah, about 45 miles north of Baghdad, illustrates the command and control problems facing the new Iraqi army, which the Americans hope can take over security in most of the country by the end of the year. It also shows that divisions within the military mirror those of Iraqi society at large.

The trouble started when a roadside bomb struck an Iraqi army convoy, which police said was made up of Kurdish soldiers. Four soldiers were killed and three were wounded, police said. U.S. military officials put the casualty figure at one dead and 12 wounded.

According to both the U.S. and Iraqi accounts, the wounded were rushed to the U.S. military hospital in Balad. Police said that as the Kurdish soldiers drove to the hospital, they fired weapons to clear the way, and one Iraqi Shiite civilian was killed.

Shiite soldiers from another Iraqi unit based in Balad rushed to the scene, and the Kurds decided to take their wounded elsewhere, Iraqi police said. Iraqi troops tried to stop them and shots were fired, killing one Shiite soldier, Iraqi police said.

The U.S. account said an Iraqi soldier from the 3rd Battalion, 1st Brigade was killed in a “confrontation” as the other Iraqi troops were trying to remove their wounded from the hospital. The U.S. statement did not explain why the troops wanted to take their wounded from the best-equipped American medical facility in the country.

A third Iraqi army unit set up a roadblock in the area and stopped the soldiers who were leaving with their wounded, the U.S. statement said.

In Basra, gunmen killed a Sunni Arab cleric and his son as they left a Friday prayer service – the second assassination in three days of Sunni leaders in the predominantly Shiite south.

On Friday, President Bush singled out Iraq’s militias as the biggest impediment to restoring stability in Iraq, saying “it’s going to be up to the government to step up and take care of that militia so that the Iraqi people are confident in the security of their country.”

Bush spoke at the White House, where he met with 10 former secretaries of state and defense from both Republican and Democratic administrations to discuss Iraq and the broader Middle East.