OLYMPIA (REUTERS) - The US Army convened a pre-trial evidentiary hearing on Wednesday for a soldier accused of shooting dead two deaf, unarmed Iraqi boys in 2007.

Sergeant First Class Michael Barbera faces two counts of premeditated murder stemming from the incident.

The court proceeding, called an Article 32 hearing, is being held at Washington state's Joint Base Lewis-McChord and is expected to last five days, Army spokesman Lieutenant Colonel Dennis Swanson said.

The hearing marks the latest high-profile international murder case against a U.S. soldier to unfold at Lewis-McChord.

Last June, US Army Staff Sergeant Robert Bales pleaded guilty to killing 16 unarmed Afghan civilians in 2012. Two months earlier, US Army Sergeant John Russell pleaded guilty to shooting dead five fellow US servicemembers at a mental health clinic in Baghdad in 2009. Both men pleaded guilty in deals that spared them the death penalty.

Barbera's alleged attack gained notoriety after a Pittsburgh newspaper in 2012 published the accounts of fellow soldiers concerned over unwarranted killings by a soldier who escaped serious punishment after an initial Army investigation.

The incident occurred on March 6, 2007 in Iraq's Diyala province. Barbera was acting as team leader when from his squad's position in a palm grove he gunned down the brothers, aged 14 and 15, who were cattle herders, the Pittsburgh Tribune-Review reported.

Shortly after, Barbera ordered his team to kill a third boy, 14, who was walking towards them. Barbera later told his superiors that the boys were insurgents, the newspaper reported. They were all deaf mutes with no known militant affiliations, according to the newspaper.

Barbera's military defence counsel is David Coombs, who also represented former soldier Chelsea Manning in the high-profile Wikileaks case. Witnesses to appear during the hearing include former members of Barbera's team, as well as Carl Prine, the Tribune-Review reporter who investigated the incident.