A US judge ordered prosecutors Wednesday to hand over hundreds of emails by officers overseeing the detention of WikiLeaks suspect Bradley Manning, who has alleged he suffered mistreatment at a Marine Corps brig.

Lawyers for Manning, a US Army private accused of passing a trove of secret government documents to the WikiLeaks website, had asked for the emails to bolster their argument that the soldier suffered illegal treatment when he was held at the Quantico Marine base in Virginia starting in 2010.

At a pre-trial hearing at Fort Meade, Maryland, Judge Denise Lind said more than 600 emails withheld by prosecutors should be handed over to the defense, though she did not explain the reason behind her decision.

The emails discuss the military's plans to respond to queries from reporters about Manning's detention, preparing for protests, changes to Manning's list of visitors and other details, according to the judge.

Wednesday's decision means the defense will have access to about 1,300 emails, including those the judge ordered released. Judge Lind said that only 12 of about 600-700 emails did not have to be handed over.

The defense had argued the emails could be pertinent to their claim that Manning was subjected to unlawful pre-trial punishment, but prosecutors had said the emails were irrelevant.

The ruling, read out by the judge during the hearing, marked the latest tug-of-war between prosecutors and defense lawyers over the release of official correspondence, reports or other information related to Manning's case.

The judge has previously pushed military prosecutors to hand over other documents in the case, saying they had to ensure Manning's lawyers had access to information that could help with their client's defense.

Manning, who attended Wednesday's hearing wearing a blue army uniform reserved for formal occasions, is scheduled to go on trial on February 4 over charges that include that he "aided the enemy" by handing classified military and State Department documents to WikiLeaks.

If convicted, Manning faces a possible life sentence.

Manning's treatment at Quantico sparked protests from his supporters as well as human rights groups.

During his stay, Manning was held under maximum security conditions in a solitary cell, where he was stripped naked and made to wear only a suicide-proof smock to bed at night.

The 24-year-old soldier was later transferred to an army prison at Fort Leavenworth, a newer, medium-security facility where he is subjected to less strict conditions.