Colleagues of a US soldier accused of giving a trove of classified material to WikiLeaks stored music, movies and games on a shared computer server, in violation of regulations, US Army officers told a hearing Sunday.

US Army Private Bradley Manning, 24, is accused of leaking hundreds of thousands of US military reports from Afghanistan and Iraq, US diplomatic cables and videos of US air strikes.

He is suspected of siphoning off the material from secure computer networks while serving as a low-ranking intelligence analyst in Iraq and providing them to WikiLeaks.

The hearing, which began at this sprawling army base on Friday and could last up to a week, aims to determine whether Manning should face a formal court-martial on charges that could send him to prison for life.

Defense attorneys sought to show that computer network security was lax at the military intelligence unit in Iraq where Manning worked from November 2009 until his arrest in May 2010.

Manning's attorneys have also said the soldier struggled with gender issues and emotional problems but his superiors repeatedly failed to take disciplinary action or revoke his top secret security clearance.

In cross-examination by the defense, the captain who oversaw information security for Manning's brigade, said soldiers stored music, movies and games on a shared server known as the "T-drive."

Captain Thomas Cherepko said he would delete the unauthorized media when he found it but it would regularly reappear. Although he notified his immediate superiors of the practice, no one was ever punished to his knowledge.

"I alerted them to the presence of it... that it's unauthorized and that the practice of putting it there needs to stop," Cherepko said

"I'm not aware of any actions that were taken."

Cherepko was asked by the defense what prevented a soldier from burning a disc on a computer with access to classified material and then just walking away with it.

"The only thing preventing that was trust, that the soldier would do what is right and not remove classified material," he said.

His testimony was backed by Captain Casey Fulton, who served with Manning in Iraq and acknowledged that soldiers regularly listened to music stored on the shared server.

Fulton was also asked by the defense about a fight between Manning and a female soldier, Specialist Jihrleah Showman, shortly before his arrest.

The captain said she was on the phone in the common work area and turned around after hearing a disturbance to see Showman pinning Manning to the ground.

"She said that he had struck her and she had a big red welt on her face," Fulton said.

Fulton ordered Manning to be removed from the work area, undergo behavioral treatment and have his weapon removed. She told the defense Manning should have been reprimanded for previous behavioral incidents.

Sergeant Chad Madaras, who shared Manning's computer work station in Iraq, said he saw a "couple" of emotional outbursts but was not aware of any counseling or discipline for the US soldier until the incident with Showman.

Madaras also said Manning did not appear to have any friends in the unit and he agreed with a defense description that he was an "outcast."

Dressed in a green camouflage uniform of the 10th Mountain Division and wearing black-rimmed glasses, Manning listened intently to the testimony and jotted down occasional notes on a legal pad.

Two other witnesses called by prosecutors declined to testify Sunday, citing their right against self-incrimination.

One of them was Sergeant First Class Paul Adkins, who was the senior non-commissioned officer in Manning's unit in Iraq.

Adkins was demoted from master sergeant to sergeant first class following the Iraq deployment for reasons that have not been made public.

Manning sent emails to Adkins in April 2010 in which he included a picture of himself dressed as a woman and said his troubles were "impacting his ability to do his job."

Anti-war activists have been staging daily vigils and rallies outside of Fort Meade in support of Manning, who has been lauded as a courageous whistleblower by his backers.