FORT MEADE, United States / Maryland (AFP) - Secret files on Guantanamo detainees that a US soldier gave to WikiLeaks were simple biographical "baseball cards" that were of no use to America's enemies, a former prosecutor at the prison testified on Tuesday.

Defence lawyers for army private Bradley Manning, who has admitted to handing WikiLeaks a trove of classified files, are trying to counter the government's claim that the soldier is guilty of espionage because he leaked documents that could threaten US national security.

The defence team Tuesday focused on more than 700 leaked files on inmates held at Guantanamo, known as "detainee assessment briefs," including five that are cited in espionage charges against Manning.

The former chief prosecutor of terror suspects held at the US prison in Guantanamo Bay, Cuba, Mr Morris Davis, told the court that the briefs contained basic biographical information about detainees that could be obtained easily through public sources.

"It is just background information. We described them as 'baseball cards' - it was just who the individual was, a 'Who's John Smith?'-type description of the individual," Mr Morris said.

The former prosecutor said while the leak may have caused "embarrassment" to Washington, he could not see how adversaries would gain any benefit from the papers.

"If they (Al-Qaeda) are trying to gain some strategic, tactical advantage, the detainee assessment brief is not the place to get it," said Mr Morris, a retired colonel and now an outspoken critic of the Guantanamo trials.

But prosecutors questioned Mr Morris's expertise in evaluating national security threats and have previously called a general to the stand who said the leaked Guantanamo papers could damage US interests.

The prosecution also argued that Manning violated the country's Espionage Act because the Guantanamo files allegedly were deemed to be highly secret or, in government parlance, "closely held."

Two other defence witnesses, described as intelligence experts, said they reviewed battlefield reports and State Department cables leaked by Manning and found that in most cases, information in the documents could be found in a Google search.

Out of 125 diplomatic cables cited in the charges against Manning, some information contained in all but two of the cables could be found online, said Charles Ganiel, who has worked with classified documents as a government employee and contractor.

And out of roughly 100 military battlefield reports disclosed by Manning, details in more than 60 of the documents were easily found on the Internet in news reports or Pentagon statements, Cassius Hall, an analyst at the US Army Intelligence and Security Command, told the court.

But under questioning by prosecutors, both Ganiel and Hall acknowledged only some details were accessible online in news reports.

Manning has already admitted giving WikiLeaks more than 700,000 secret military intelligence files and diplomatic cables in the worst leak of classified information in US history.

But he is fighting 21 other charges, including the most serious count that he knew he was "aiding the enemy" by unloading the files to the secret-spilling website. That charge carries a maximum penalty of life in prison.

Manning's defence team on Monday filed motions asking the military judge, Colonel Denise Lind, to dismiss the "aiding the enemy" charge and several other counts on grounds that the prosecution lacked evidence.

The outcome of the court martial, which is being held at Fort Meade in Maryland near Washington DC, will hinge in part on Manning's state of mind before the massive leak, as the government must show he knew the documents could fall into Al-Qaeda's hands.

Another witness testified on Monday that months before the disclosures, the soldier, now aged 25, spoke of trying to use knowledge from his extensive reading to help save lives in the Iraq war.

Manning's online chat log was presented during testimony from Lauren McNamara, a transgender woman who had online conversations with the soldier.

According to the log, Manning said: "What's even better with my current position is that I can apply what I learn to provide more information to my officers and commanders, and hopefully save lives." The log was part of the defence's effort to paint a picture of Manning as a principled young man who leaked files because he cared about his country and the effect of its policies.

For the "aiding the enemy" charge, the judge has ruled the government must prove Manning had "general evil intent" and he "had to know he was dealing, directly or indirectly, with an enemy of the United States."