The Baghdad-based officer described the information this week in an interview, saying the intelligence was gleaned from captured militia fighters and other sources. He spoke on condition of anonymity to discuss sensitive intelligence.

The officer on Wednesday provided Iraq's national security adviser with several lists of the assassination teams' expected targets. He said the targets include many judges but would not otherwise identify them.

Iraq's intelligence service is preparing operations to determine where and when the special group fighters will enter the country and is to provide an assessment to Prime Minister Nouri al-Maliki.

The U.S. official acknowledged disclosing the information in an attempt to pressure Iran to suspend the training and prevent the militia fighters from returning to Iraq.

The U.S. military wants the Iraqi government to take steps to protect the targets. "Wanted" posters picturing men believed to be heading the special groups are being posted around Baghdad, the military officer said.

The fighters are expected to return to Iraq between now and October, but the officer said no intelligence suggested they were in Iraq yet.

The information came from militia fighters captured in Iraq and other sources in the country that the officer would not describe.

Many of the fighters fled to Iran this spring after Iraqi government forces cracked down first on militia sanctuaries in Basra and Baghdad's Sadr City district, then in Amarah and now in Diyala province, the military officer said.

The officer said training is going on in at least four locations in Iran: Qom, Tehran, Ahvaz and Mashhad.

Iran, Hezbollah's benefactor, has denied giving any support to Shiite extremists in Iraq.

The number of "special group criminals" - the U.S. name for Iraqi fighters sponsored by Iran - is unknown but is estimated in the hundreds and possibly more than 1,000.

According to the officer, the training camps are operating under the direction of Quds force commander Brig. Gen. Ghassem Soleimani, with the knowledge and approval of Iran's supreme leader, Ayatollah Ali Khamenei. The Quds force is a branch of Iran's Revolutionary Guard.

Second Blast Targets Shiite Pilgrims; 4 Die

A van packed with explosives blew up yesterday at a bus station in Balad, north of Baghdad, where Shiite pilgrims had stopped for the night, killing four people and wounding dozens, U.S. and Iraqi officials said.

The blast happened a day after a female suicide bomber struck Shiite pilgrims traveling to Karbala for a major religious festival, killing at least 18.

The attacks raised concern that extremists are seeking to re-ignite the firestorm of sectarian massacres that took Iraq to the brink of civil war two years ago before the U.S. rushed reinforcements.

Hundreds of thousands of Shiites from across Iraq have been traveling by foot or vehicle to Karbala, 50 miles south of Baghdad, for the religious festival.

The U.S. military reported the deaths of two more service members - a Marine in combat the day before west of Baghdad and a soldier who died yesterday of "non-battle-related causes" in the capital.

Those deaths raised to at least 4,143 the number of U.S. military personnel who have died in the war since it began in March 2003, according to a count by the Associated Press.

- AP