Manning's lawyers move to have the 22 charges against him dismissed due to treatment during his detention likened to torture

Bradley Manning, the suspected WikiLeaks source, is seeking to call several military psychiatrists to testify that he was held in custodial conditions likened to torture against their professional advice.

Manning's defence lawyers have lodged a motion with the military court in Fort Meade, Maryland requesting the appearance of seven medical and other experts at the next pretrial hearing scheduled for 1 October.

The defence team, led by civilian lawyer David Coombs, is trying to have all 22 charges against Manning thrown out of court on grounds that he was subjected to illegal pretrial treatment in violation of the constitutional prohibition of cruel and unusual punishment.

Manning is accused of being responsible for the biggest leak of state secrets in US history. Hundreds of thousands of diplomatic cables from US embassies around the world, as well as warlogs from Afghanistan and Iraq, were published by the whistleblowing website WikiLeaks.

After his arrest in May 2010 at a military base near Baghdad, the young soldier was held at the Quantico marine base in Virginia.

For a period of about eight months at Quantico, Manning was subjected to extraordinarily harsh conditions. This was done, the military claimed, for his own protection under a so-called "prevention of injury" order or POI.

The unidentified witnesses that Coombs wants to call include a military psychiatrist who consistently recommended to Manning's captors at the brig at Quantico that the prisoner should be removed from restrictive conditions. But his advice was ignored and Manning continued to be subjected to solitary confinement, being stripped naked, held in a bare cell and made to wear a rough smock at night.

Witnesses will testify, the defence motion states, that when the psychiatrists objected to the conditions, they were told by the military chiefs in the brig: "We will do whatever we want to do."

The defence also wants to call witnesses from Fort Leavenworth in Kansas where Manning was moved in April 2011 following an international outcry about his treatment.

After the move, the soldier was allowed much greater freedom under medium-security arrangements. The defence argues that his successful transfer shows "he was improperly held to begin with".

October's hearing on Manning's treatment at Quantico is a crucial last chance for his defence team to ameliorate some of the charges against him ahead of the full court martial trial that is likely to take place early in the new year. It is not clear, however, how far the judge presiding over the proceedings, Colonel Denise Lind, will be prepared to go.

At the most recent pretrial hearing earlier this month, she refused to allow Juan Mendez, the UN's special rapporteur on torture, to testify, saying it was irrelevant to the issue of illegal punishment.

Mendez investigated the conditions at Quantico and concluded that the soldier had been held in cruel and inhuman conditions.

The defence motion calling for the case against Manning to be dismissed is brought under Article 13 of the Uniform Code of Military Justice. It states that "no person, while being held for trial, may be subjected to punishment or penalty other than arrest or confinement upon the charges pending against him, nor shall the arrest or confinement imposed upon him be any more rigorous than the circumstances required to insure his presence."

Under Article 13, if a judge decides that a member of the armed forces has been illegally punished before trial, the judge can grant the prisoner credit on the amount of time they have already served in custody, or can even dismiss all charges outright.