President Barack Obama's comments about the soldier accused of the biggest intelligence leak in US history were prejudicial and sought to harm the suspect's defense, a court heard Tuesday.

Other top figures, including Secretary of State Hillary Clinton and retired admiral Mike Mullen, the former head of the US Joint Chiefs of Staff, also made ill-advised remarks about Army Private Bradley Manning, it was alleged.

Obama's comment that Manning "broke the law," made at a political fundraiser in California last April, and other public statements were deliberately designed to inflict damage on the defense, according to civilian attorney David Coombs.

These are "people who should know better," Coombs said at Manning's pre-trial hearing at the Fort Meade military base in Maryland, naming the US president and referring to remarks made by top US diplomat Clinton and Mullen.

"Members of the government have taken the opportunity to throw comments out to the press that were very prejudicial. It was done purposefully and was unfortunate for us," Coombs said.

"Even though he is the commander-in-chief he does not have influence in this courtroom," the lawyer said, in a pointed reference to Obama.

Manning, 24, could spend the rest of his life in jail if he is convicted of aiding the enemy by handing hundreds of thousands of classified documents to WikiLeaks, the notorious file-sharing website.

The soldier was serving as an intelligence analyst near Baghdad when he was arrested in May 2010 an accused of releasing a trove of classified logs relating to Iraq and Afghanistan and State Department diplomatic cables.

The massive document dump to WikiLeaks triggered a diplomatic firestorm that hugely embarrassed American officials and rankled the nation's allies.

Manning, who is attending this week's hearing at Fort Meade, was initially sent to a US military prison in Kuwait, but was later held in custody at garrisons in Virginia and latterly, Kansas.

He has not yet entered a plea in the case and his trial is tentatively due to start in September.

On Monday, the first day of the five-day pre-trial hearing, Manning's defense team argued that government lawyers must prove that the soldier intended to help Al-Qaeda by passing secret government documents to WikiLeaks.

The prosecution, however, has countered that they only have to show that Manning knew Al-Qaeda might see the sensitive files after they were posted on the Internet.

A small crowd of Manning supporters were at Tuesday's hearing where it emerged that the military panel likely to decide the accused's fate will have to answer more than 100 questions during a rigorous pre-trial screening process.

The procedure is meant to ensure there is no major risk of Manning being a victim of prejudice from the ruling panel, the military equivalent of a jury.

The questions will range from asking would-be jurors' if their reading habits include fiction focused on military intelligence, whether they've ever taken part in a protest march, to what voluntary work, if any, they undertake.

The full list of questions was not released to reporters covering the hearing but some of the details emerged in arguments heard during judicial argument.

A member of the prosecution said nine questions related to the subject of homosexuality -- Manning is gay.

Army judge Colonel Denise Lind refused a defense team request that jurors be asked if they backed gay marriage, but a question about whether they agree with the repeal last year of the military's "don't ask, don't tell" policy, which prohibited gays from serving openly in the armed forces, was allowed.

Manning could opt for a single judge to rule in the case, but unless he does so a panel of between five and 12 service personnel will weigh the verdict.