A year and a half after his arrest, Bradley Manning, the US soldier accused of turning hundreds of thousands of classified US documents over to WikiLeaks, gets his first day in court on Friday.

Manning, who turns 24 on Saturday, is scheduled to appear at a preliminary military hearing at Fort Meade near Baltimore, Maryland, the headquarters of the top secret National Security Agency.

Manning is accused of supplying WikiLeaks with US diplomatic cables, videos and military reports from Afghanistan and Iraq while serving as an intelligence analyst on a military base near Baghdad between November 2009 and May 2010.

A private first class in the US Army, Manning was arrested on May 26, 2010 and has been in US military custody since then in Kuwait, at a US Marine Corps base in Quantico, Virginia, and at Fort Leavenworth in Kansas.

He is to appear on Friday at what is known as an "Article 32 hearing," which could last as many as five days and is the first step towards a court-martial that could see him sentenced to prison for the rest of his life.

According to Manning's lead counsel, David Coombs, the hearing "provides the defense with an opportunity to test the relative strengths and weaknesses of the government's case."

The US Army for its part said the hearing is "similar to a civilian grand jury, with additional rights afforded to the accused" including the right to cross-examine prosecution witnesses and to have evidence produced.

A request by Coombs, however, for the appearance of 48 witnesses at the Article 32 hearing was met with the rejection of all but 10 who were also on the government's list, according to the lawyer.

Among those Coombs was hoping to see testify were Secretary of State Hillary Clinton, former Defense Secretary Robert Gates and President Barack Obama.

Their names were redacted from a 20-page document seen by AFP but their identities were clear from the accompanying descriptions.

The document said Obama, listed as witness number 36, should be compelled to appear for having said in April that Manning "broke the law," remarks which the defense maintains were inappropriate given his position as commander-in-chief.

"He cannot have a fair trial in the military justice system because President Obama has already pronounced him guilty," Kevin Zeese, a Bradley Manning Support Group lawyer, told AFP.

Clinton should be called, the document argues, because she "will testify that although the leaks were embarrassing for the administration that she concurs with... opinion that they did not represent significant consequences to foreign policy."

And Gates "will testify that the initial public descriptions of the harm to foreign policy due to the publication of diplomatic cables were 'fairly significantly overwrought,'" the document said.

Manning is facing a battery of charges, the most serious being aiding the enemy, which could land him in prison for the rest of his life.

Other charges include "wrongfully causing intelligence to be published on the Internet," theft of public property or records and violating army security regulations.

Manning is the only suspect facing trial for the massive intelligence breach which led to an embarrassing daily drip of diplomatic revelations and military secrets in newspapers and websites around the world.

WikiLeaks founder Julian Assange, under house arrest in Britain awaiting potential extradition to Sweden to face sexual assault charges, has denied knowing the source of the leaks, but has defended Manning as a victim of US government mistreatment and raised funds for his defense.

Manning was transferred to Fort Leavenworth in April following criticism by his supporters and human rights groups of the conditions of his detention at Quantico, where he spent much of his incarceration in solitary confinement.

Following the Article 32 hearing, the investigating officer will recommend whether a court-martial should go ahead. If it does proceed, it is not expected to begin for several months.