BAGHDAD, Iraq — Iraqi officials suspect that about 50 U.S.-trained Iraqi soldiers slain by insurgents — many of them execution-style — may have been set up by rebel infiltrators in their ranks.
Jordanian terrorist Abu Musab al-Zarqawi's group claimed responsibility for the weekend attack, the deadliest ambush of the 18-month insurgency. The claim was posted Sunday on an Islamist Web site but its authenticity could not be confirmed.
On Monday, a suicide car bomber attacked a U.S. convoy in Khaldiyah, a town about 50 miles west of the capital, destroying at least two Humvees. Police said there were American casualties, but the number was not immediately known. The U.S. military had no immediate comment.
In Baghdad, a car bomb targeting an Australian military convoy exploded near the Australian Embassy, killing three Iraqis and wounding eight others, including three Australian soldiers, according to Iraqi and Australian officials.
Al-Zarqawi's group also claimed responsibility for that attack in a statement posted on an Islamic Web site Monday. It was impossible to verify the claim's authenticity.
"The mission will still be able to carry out its task," Australian Defense Force spokesman Brig. Mike Hannan told reporters in the capital of Canberra.
A separate roadside bomb killed one American soldier and wounded five others in western Baghdad.
An Estonian soldier was killed during an ambush Monday while patrolling outside the Iraqi capital, according to Marko Mihkelson, chairman of the Estonian parliament's Foreign Affairs committee. Several other Estonians were believed to have been wounded, but the nature of their injuries was unknown.
The soldier was the second to die this year from Estonia, which has 45 soldiers in Iraq.
The 50 unarmed Iraqi soldiers were killed on their way home after completing a training course at the Kirkush military camp northeast of Baghdad when their buses were stopped Saturday evening by rebels about 95 miles east of Baghdad, Interior Ministry spokesman Adnan Abdul-Rahman said.
Some accounts by police said the rebels were dressed in Iraqi military uniforms. The insurgents forced many of the soldiers to lie down on the ground and then shot them in the head, officials said Sunday.
There was confusion over the precise number of Iraqi soldiers killed in the ambush, although the Iraqi National Guard said 48 troops and three drivers were killed.
Abdul-Rahman said 37 bodies were found Sunday on the ground with their hands behind their backs, shot execution-style. Twelve others were found in a burned bus, he said. Some officials quoted witnesses as saying insurgents fired rocket-propelled grenades at one bus.
"After inspection, we found out that they were shot after being ordered to lay down on the earth," Gen. Walid al-Azzawi, commander of the Diyala provincial police, said, adding that the bodies were laid out in four rows, with 12 bodies in each row.
The killing of so many Iraqi soldiers in such an apparently sure-footed operation reinforced American and Iraqi suspicions that the country's security services have been infiltrated by insurgents.
Iraqi police and soldiers have been increasingly targeted by insurgents, mostly with car bombs and mortar shells. However, the fact that the insurgents were able to strike at so many unarmed soldiers in such a remote region suggested the guerrillas may have had advance word on the soldiers' travel.
"There was probably collusion among the soldiers or other groups," Diyala's deputy Gov. Aqil Hamid al-Adili told Al-Arabiya television. "Otherwise, the gunmen would not have gotten the information about the soldiers' departure from their training camp and that they were unarmed."
Last week, a U.S. defense official said in Washington that some members of the Iraqi security services have developed sympathies and contacts with the guerrillas. In other instances, infiltrators were sent to join the security services, the official said on condition of anonymity.
He cited a mortar attack Tuesday on an Iraqi National Guard compound north of Baghdad as a possible inside job. The attackers apparently knew when and where the soldiers were gathering and dropped mortar rounds in the middle of their formation. At least four Iraqis were killed and 80 wounded.
The extent of rebel infiltration is unknown. However, it raises concern about the American strategy of handing over more responsibility to Iraqi security forces so U.S. forces could be drawn down.
In a Web site posting, the al-Qaida in Iraq claimed responsibility for the ambush, saying "God enabled the Mujahedeen to kill all" the soldiers and "seize two cars and money."
Al-Zarqawi and his movement are believed to be behind dozens of attacks on Iraqi and U.S.-led forces and kidnappings of foreigners. Many of those hostages, including three Americans, have been beheaded — some purportedly by al-Zarqawi himself.
The United States has put a $25 million bounty on al-Zarqawi — the same amount as for Osama bin Laden. U.S. officials believe al-Zarqawi's group is based in Fallujah, an insurgent bastion 40 miles west of Baghdad.
Elsewhere, a U.S. diplomat was killed Sunday morning when a rebel-fired rocket or mortar shell crashed into an American base near the Baghdad airport, the U.S. Embassy announced.
Edward Seitz, 41, an agent with the State Department's Bureau of Diplomatic Security, was believed to be the first U.S. diplomat killed in Iraq since the war began in 2003. Al-Jazeera television reported Sunday that the militant Islamic Army of Iraq claimed responsibility for the attack.
One American soldier also was wounded in the pre-dawn attack that killed Seitz. The attack occurred at Camp Victory, the headquarters of the U.S.-led coalition's ground forces command.
Seitz was believed to be the first full-time State Department officer killed in Iraq. In October 2003, a female U.S. Foreign Service officer was severely wounded in the arm in a rocket barrage on the Rasheed Hotel.
Associated Press reporters Rawya Rageh in Baghdad, Hanna Daghestani in Baqouba and Abdul Razzak Jabr in Kut contributed to this report.