A speech freedom advocacy group has released audio of Bradley Manning’s testimony about his motives for leaking secret US government documents to WikiLeaks. It marks the first time the public has heard Manning's voice since his 2010 arrest.

Defying the military's ban on making recordings at Manning’s pre-trial tribunal at the military court at Fort Meade, the Freedom of the Press Foundation (FPF) has released Manning’s February account to the judge explaining why he exposed military secrets.

"We hope this recording will shed light on one of the most secret court trials in recent history, in which the government is putting on trial a concerned government employee whose only stated goal was to bring attention to what he viewed as serious governmental misconduct and criminal activity," the FPF said in a statement.

While unofficial transcripts of the statement are available, this is the first time anyone outside the court has heard Manning’s own explanation of how and why he gave the Apache helicopter video, Afghanistan and Iraq Wars Logs and State Department Diplomatic Cables to WikiLeaks.

Manning justifies his actions with a firm belief that what he identifies as US government wrongdoings need to be exposed in order to “spark a domestic debate on the role of the military and our foreign policy in general as it related to Iraq and Afghanistan.”

In the recording he goes on to accuse the army of “not valu[ing] human life," comparing servicemen "to a child torturing ants with a magnifying glass."

In regards to the “Collateral Murder” video, which shows US Apache helicopters opening fire on and killing civilians, including journalists, Manning said “the most alarming aspect of the video to me, however, was the seemingly delightful bloodlust they appeared to have.”

The attacks footage received worldwide coverage following the release of 39 minutes of classified cockpit gunsight material in 2010, starting the controversy surrounding WikiLeaks and its whistleblowing founder Julian Assange.

Because recording is prohibited at Manning’s hearings, the Pentagon is pursuing measures that would strengthen security and prevent information leaks from the trial.

Military judge Denise Lind, who is trying Manning’s case, has been informed by the Department of Defense that there was "a violation of the rules for the court," a spokesman said in a statement sent to AFP, and that the “US Army is currently reviewing the procedures set in place to safeguard the security and integrity of the legal proceedings and ensure PFC Manning receives a fair and impartial trial.”

Twenty-five-year-old Private First Class Manning has been held in US military custody following his arrest in May 2010. He has pleaded guilty to 10 of the 22 charges set against him. If convicted, he could face 20 years in jail. He is pending trial as the prosecution still intends to pursue the 12 remaining charges.