BAGHDAD, July 1: Three US soldiers killed by guerillas south of Baghdad last month had been left alone at a checkpoint in violation of military procedure, a US military spokeswoman said on Saturday.

An investigation is already under way into how the soldiers came to be on their own in an armoured Humvee vehicle in an al Qaeda hotspot known as the “Triangle of Death” as night fell.

Militants abducted and killed two of them in an attack in which the third soldier also died.

“A lone vehicle does not fit standard operating procedures and does not match published guidance,” Lieutenant Colonel Michelle Martin-Hing said.

“The investigation will look at the circumstances surrounding this event and how it was that this vehicle was there by itself.”

Major General James Thurman, commander of US-led forces in the Baghdad area, ordered the probe into the deaths of Privates First Class Kristian Menchaca, 23, Thomas Tucker, 25 and David Babineau, 25.

He has been reluctant to comment on whether a breach in military procedure made them vulnerable to attack, saying this will form part of the investigation.

The mutilated and booby-trapped bodies of Menchaca and Tucker were found three days after militants captured them on June 16 near the village of Yusufiya. Babineau was killed in the attack on the checkpoint on a canal bridge.

The Army Times quoted Martin-Hing as saying that “no one has a good answer” for the apparent lapse in security procedure.

The newspaper said in its latest edition that “a three- Humvee minimum has evolved as the standard for combat patrols and convoys”.

Martin-Hing told the newspaper that two Humvees, part of the same patrol, had been manning a traffic control point slightly to the northeast of the bridge crossing. They were in radio communication with the lone Humvee but not in visual range.

Thurman said this week it took 15 minutes for a quick reaction force to reach the site after US soldiers in the area heard small arms fire and explosions near the checkpoint.—Reuters