Security at the military unit in Iraq where alleged WikiLeaks source Bradley Manning worked was so lax that soldiers could watch pirated movies on army intelligence computers, it has been revealed.

Speaking on day three of the preliminary hearing regarding Private Manning, a senior officer in his "sensitive compartmented information facility" (SCIF)said it was common for analysts to bring in DVDs bought from Iraqis.

They also stored music and played games on computers used for handling classified information.

The disclosure, by Captain Casey Fulton, is the latest to indicate loose controls within the unit where Manning, 24, served as an intelligence analyst.

It has previously emerged that passwords to secure computers were left on Post-it notes stuck on terminals and that there was no system for checking that classified information was not removed from the building.

Fulton said she did not know it was wrong for soldiers to store music and films on a secured shared drive.

Under cross-examination, Fulton said that in her opinion the soldier should have been issued with a "derog" – a disciplinary notice – in December 2009 when he was involved in an incident in which he overturned a table and then made to grab a gun from a gun rack.She also said that it was her view that Manning should have been issued a "derog" on 7 May 2010 when he assaulted a fellow intelligence analyst. Fulton was in the unit at the time when the assault happened.

Earlier that day, she told the hearing, she had seen Manning on the floor curled up in a ball in a side room in the unit. Later that evening she had seen Manning pinned to the ground by his fellow worker, a female analyst called Specialist Shulman.

Others in the unit had witnessed Manning hit Shulman, and she had a red welt on her face, Fulton said.

Under questioning, Fulton confirmed that had a "derog" been issued, Manning could have had his security clearance withdrawn and he would no longer have access to the databases of confidential information.

Manning faces a 22-count indictment, including charges of aiding the enemy, in relation to the leak last year of 250,000 classified US diplomatic cables to WikiLeaks. The current hearing is to establish whether he should face a full court-martial over the alleged crimes.