Nidal Hasan, charged with killing 13 people and wounding 31 in a November 2009 shooting spree at Fort Hood, Texas, is pictured in an undated Bell County Sheriff's Office photograph. [Photo/Agencies]

HOUSTON -- A US Army psychiatrist accused of killing 13 and injuring more than 30 others at the Fort Hood Army Base in the US state of Texas in 2009 admitted committing the violence in front of a jury on Tuesday.

"The evidence will clearly show that I am the shooter," Major Nidal Malik Hasan, a 42-year-old Army psychiatrist, told the jury of 13 officers at a court martial.

In a short statement that lasted less than two minutes, he repeated his radical views.

"We, the mujahedeen, are imperfect Muslims trying to establish a perfect religion in the land of the supreme God," he said, "I apologize for any mistakes in this endeavor."

The US-born Muslim was due to be deployed to Afghanistan weeks after the attack. And he had wanted to use a "defense of others" strategy at trial, arguing that he shot US troops to protect Taliban fighters in Afghanistan from US assaults. But the military judge for the court martial, Colonel Tara Osborn, forbade him from using that defense.

Tuesday's long-awaited trial was held in the heavily fortified military base where armed guards stood in doorways and stacks of shock-absorbing barriers piled around the courthouse.

Hasan was interrogated before jurors in a wheelchair as he was shot in the back by military police during the rampage and was paralyzed from the waist down.

Hasan fired his lawyers and acted as his own attorney. He had released several statements prior to the trial, explaining his motive and criticizing the US government's "anti-Islam" policies.

However, he raised few objections as military prosecutors began to present a methodical, detailed case. He asked two witnesses questions as testimony was heard from eight witnesses during the first morning session of the trial.

He faces 13 charges of premeditated murder and 32 charges of attempted premeditated murder in the November 2009 attack at the Texas Army base.

Hasan could be sentenced to death if convicted. The last execution carried out by the US military was in 1961.

Born in the eastern US state of Virginia to Palestinian parents, Hasan joined the Army in 1995. An FBI report shows that he first exhibited signs of radical Islamic views while working at Walter Reed Army Medical Center from 2003 to 2006.

Hasan attended a mosque where radical US-born cleric Anwar al-Awlaki once worked. The latter was a key figure in Al-Qaida in the Arabian Peninsula before he was killed in a 2011 drone strike in Yemen. Hasan has exchanged more than a dozen emails with Anwar al-Awlaki since December 2008.