LONDON (AFP) - WikiLeaks founder Julian Assange on Tuesday condemned the "show trial" of Bradley Manning, the US soldier accused of helping Al-Qaeda by leaking a hoard of secret files to the whistleblowing website.

In a statement posted on the WikiLeaks site, Assange said the court martial which began near Washington on Monday did not represent justice for the 25-year-old army private.

"This is not justice; never could this be justice. The verdict was ordained long ago," he wrote.

"Its function is not to determine questions such as guilt or innocence, or truth or falsehood.

"It is a public relations exercise, designed to provide the government with an alibi for posterity. It is a show of wasteful vengeance; a theatrical warning to people of conscience."

Assange is currently holed up at the Ecuadorian embassy in London after taking refuge in June last year to escape extradition to Sweden, where he faces allegations of sexual assault.

He claims the allegations are politically motivated and linked to the release by WikiLeaks of the classified documents allegedly leaked by Manning, which caused huge embarrassment to the US government.

Assange condemned the "abuse" of Manning, who he described as "the most prominent political prisoner in modern US history".

The soldier's lawyers have successfully argued that he has been subjected to unduly harsh detention methods since his arrest while serving in Iraq in 2010.

"Against all of this, it would be tempting to look on the eventual commencement of his trial as a mercy. But that is hard to do," Assange wrote.

The Australian former computer hacker said the pre-trial hearings had "comprehensively eliminated any meaningful uncertainty, inflicting pre-emptive bans on every defence argument that had any chance of success".

"It is fair to call what is happening to Bradley Manning a 'show trial'." Manning has pleaded guilty to several offences but denies the most serious charge - that he knowingly aided the enemy, chiefly Al-Qaeda and late terror chief Osama bin Laden.

Assange said the documents leak to Wikileaks was "the single most important disclosure of subjugated history, ever".

"Bradley Manning is accused of being a whistleblower, a good man, who cared for others and who followed higher orders," he said. "But that is not the language the prosecution uses."