A US Army investigator said Monday that 10,000 State Department cables found on a computer used by Bradley Manning were apparently not passed on to WikiLeaks because they were in a corrupted file.

Manning, a 24-year-old army private, is accused of giving WikiLeaks a massive cache of US military reports from Iraq and Afghanistan, diplomatic cables from US embassies around the world, Guantanamo detainee assessments and videos of US air strikes.

Among the classified documents Manning is suspected of passing on to WikiLeaks are some 260,000 State Department cables which led to an embarrassing string of revelations for the United States and other governments.

Special Agent David Shaver of the US Army's Computer Crimes Investigative Unit, told a hearing being held to decide if Manning should face a court-martial that an additional 10,000 unpublished cables were found on one of his computers.

He said the cables were compressed in a zip file that had apparently been corrupted.

Asked by prosecutors if this is why the 10,000 cables were not part of the batch released by WikiLeaks, Shaver said it would be logical to assume so.

Shaver also said an additional 100,000 complete State Department cables which had been encoded were found on a computer used by Manning between November 2009, when he was deployed to Iraq, and May 2010, when he was arrested.

The 100,000 cables were present in unallocated space on the device, indicating that the files had been deleted, and while they were found on a machine Manning had used they could not be directly linked to his user profile, he said.

"You cannot say it was my client who accessed this information?" Captain Paul Bouchard, a military-appointed defense attorney, asked Shaver. "You did not find any forensic evidence that this information was sent to anyone?"

"No sir," the army digital forensic expert replied to both questions.

At one point during Shaver's testimony, the courtroom was cleared -- over defense objections -- of the general public and the media for a discussion of classified material.

Manning, his civilian and military-appointed attorneys, US Army prosecutors, the presiding officer, representatives of unspecified US government agencies and security and legal staff were the only ones present during the closed session.

The testimony by Shaver, who heads the CCIU's digital forensics and research branch, has been the most compelling yet against the US soldier accused of one of the most serious intelligence breaches in US history.

Manning could face life in prison if convicted of "aiding the enemy," the most serious of the 22 charges he is facing.

Defense attorneys have argued that Manning 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.

His defense attorneys have also suggested that Manning, who is gay, had difficulty serving in a US military that was operating under the "Don't Ask, Don't Tell" policy towards homosexuals which has since been repealed.

The pre-trial hearing is being held to decide whether Manning should face a court-martial -- a determination to be made by the presiding officer, US Army Lieutenant Colonel Paul Almanza.

Almanza is not expected to make his recommendation until several weeks after the conclusion of the hearing, which began Friday and could last several more days.

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.