State Department cables and other documents released by WikiLeaks were found on computers used by Bradley Manning, accused of giving a trove of classified material to the secret-spilling site, a US Army cyber expert said on Sunday.

Special Agent David Shaver of the Computer Crimes Investigative Unit (CCIU) provided the most compelling evidence yet against the army private accused of one of the most serious intelligence breaches in US history.

Shaver's testimony came on the third day of a hearing being held at this army base to decide whether the 24-year-old should face a court-martial on charges that could send him to prison for life.

Manning is accused of leaking hundreds of thousands of US military reports from Afghanistan and Iraq, US diplomatic cables and videos of US air strikes to WikiLeaks.

Shaver, who heads the CCIU's digital forensics and research branch, examined two Windows-powered computers used by Manning during his November 2009 to May 2010 deployment to Iraq as a low-ranking intelligence analyst.

He said frequent keyword searches had been conducted on the computers with Manning's user profile for ‘WikiLeaks’ and ‘Julian Assange,’ the Australian founder of the site, the first dating from December 1, 2009.

Given Manning's role as an intelligence analyst focusing on Iraq, "searches like WikiLeaks, Iceland and Julian Assange seemed a little out of place," Shaver said.

The keyword searches were performed on the basis of instant message chat logs between Manning and Adrian Lamo, a former computer hacker who turned the logs over to US authorities.

Some 10,000 complete State Department cables were found in a zip file on one of the computers, along with a listing of 251,288 individual ‘message record numbers’ for State Department cables, Shaver said.

"To my knowledge, WikiLeaks released 251,287 cables," he said, adding that one file was partially corrupted. Guantanamo detainee assessments found on Manning's machines were identical to those released by WikiLeaks.

An unauthorized tool was also found on Manning's computers, which is used to "download large amounts of files in a short period of time," Shaver said.

"This was all under PFC Manning's user profile?" asked Captain Joe Morrow, a US Army prosecutor.

‘Yes sir,’ Shaver replied.

Shaver is due to be cross-examined by Manning's defense attorneys when the hearing resumes on Monday.

Other witnesses testified that soldiers in Manning's unit in Iraq stored music, movies and games on a shared computer server, in violation of regulations.

Defense attorneys elicited the admission from officers in Manning's military intelligence unit in a bid to show that computer network security was lax at the base.

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

Captain Casey Fulton told the court about a fight Manning had with a female soldier, Specialist Jihrleah Showman, shortly before his arrest.

"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 the soldier 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, Manning listened intently to the testimony and jotted down occasional notes on a legal pad.

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

One of them was Sergeant First Class Paul Adkins, who 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 protests outside of Fort Meade in support of Manning, who has been lauded as a courageous whistleblower by his backers.