A military judge on Monday ruled that self-incriminating statements made to US interrogators could be admitted as evidence in the war crimes trial of an Al Qaeda operative accused of murdering an American soldier in Afghanistan.

The ruling came in a special courtroom at the US Naval Base at Guantánamo Bay, Cuba, where officials are preparing for the first contested military commission trial of the Obama presidency. It is scheduled to begin on Tuesday.

Facing trial is Omar Khadr for allegedly throwing a hand grenade that killed a US special forces soldier and partially blinded another after a firefight near Khost, Afghanistan, in July 2002.

Mr. Khadr was 15 years old at the time. He denies throwing the grenade.

His lawyers object to the commission trial, saying that because of his young age at the time of his capture he should be treated as a child soldier who is not fully responsible for his actions.

They also argued that he faced brutal mistreatment and threats of rape by US interrogators and that any statements he made to military officials should not be used against him at trial.

Prosecutors countered that Khadr was not mistreated and that statements he made accepting responsibility for the grenade attack were not coerced.

On Monday, the military judge presiding over the case said Khadr’s statements could be used as evidence at the commission trial.

'Am I an animal?'

Earlier on Monday, in a pretrial hearing, prosecutors presented a video of Khadr surrounded by seven military guards who were trying to weigh him in compliance with requirements of the International Committee of the Red Cross. The prosecutors introduced the video in an attempt to show that Khadr had not been mistreated while in US custody.

Khadr’s lawyer said the video supported his claims of abusive treatment.

According to a Reuters report, Khadr refused to step on the scale and began to cry. “The rules don’t say to capture a kid and deprive him of all his rights … am I an animal,” Khadr asked.

Khadr’s lawyer, US Army Lt. Col. Jon Jackson later urged the judge to bar from the trial any statements produced by interrogators in Afghanistan or Guantánamo. “Tell the government that they cannot and will not benefit from someone being threatened with rape and torture,” he said, according to a Reuters report.

Military prosecutors have charged Khadr with murder, conspiring with Al Qaeda and providing material support to the terror group. The charges include throwing the hand grenade that killed US Army Sgt. Christopher Speer. Khadr is also charged with the attempted murder of US forces by converting land mines into improvised explosive devices and hiding them along the road. In addition, he is charged with conducting surveillance of US troop movements in Afghanistan.

If convicted he faces up to life in prison.

A test for trial of alleged 9/11 mastermind

The Khadr trial could become an important test for the Obama administration, which is still struggling to find an appropriate location and court to try suspected 9/11 mastermind Khaled Shaikh Mohammed.

Attorney General Eric Holder had announced that Mr. Mohammed would be tried in federal court in New York City, but that plan was scrapped after local officials objected.

The Guantánamo trial also underscores the failure of President Obama to fulfill a pledge on his first day in the White House that he would close Guantánamo within a year. The effort was complicated by congressional opposition to relocating Guantánamo detainees to US soil and the increase in violent Al Qaeda-linked activities in Yemen.

Khadr's story

Khadr was born in Toronto and is a Canadian citizen.

He moved with his family to Pakistan when he was two years old. His father was allegedly an Al Qaeda ally and associate of Osama bin Laden. After the 9/11 attacks, Khadr, then 14, followed his father into Afghanistan. His father was killed.

Khadr’s lawyers argue that the teen was under the strong influence of his father when he joined the fight in Afghanistan. He is now 23 years old and has lived a third of his life behind bars at Guantanamo.

Defense lawyers had tried a last-ditch effort to derail the military commission trial, appealing on Friday to the US Supreme Court. The high court turned the appeal aside without comment.

On Aug. 4, a three-judge federal appeals court panel also rejected Khadr’s case. The panel said that Khadr must wait until after a final verdict in his trial before he can file an appeal challenging the constitutionality of the military commission process.

Ruling for bin Laden's cook

Also on Monday, a military judge accepted a plea deal that limited the sentence of a former bin Laden cook and body guard. In an unusual move, the judge ordered the agreement sealed.

The secrecy was requested by military prosecutors, but was also agreed to by lawyers for the defendant, Ibrahim al Qosi.

Mr. al Qosi pleaded guilty July 7 to one count of conspiracy and one count of providing material support to Al Qaeda. Had he stood trial and been convicted he could have faced life in prison.