WIKILEAKS founder Julian Assange has described Bradley Manning's conviction for espionage as "national security extremism".
A military court in the United States found Manning guilty of 20 counts of espionage after he leaked highly classified material to Wikileaks.
While Manning was found not guilty of the most serious charges of aiding the enemy, he could still face the rest of his life in prison over the espionage convictions.
The 25-year-old former army intelligence analyst was expected to be sentenced on Thursday (AEST).
Mr Assange, who remains holed up in London's Ecuadorian embassy to avoid extradition to Sweden, said Manning should have been treated as a whistleblower, adding his conviction had set a "dangerous precedent".
"Bradley Manning's alleged disclosures have exposed war crimes, sparked revolutions and induced democratic reform. He is the quintessential whistleblower," said Mr Assange, who will stand for the Senate at the next election as a candidate for the newly-formed Wikileaks Party.
"This is the first espionage conviction against a whistleblower in the United States. It is a short-sighted judgment that cannot be tolerated and it must be reversed."
Mr Assange went on to accuse the US Government of stripping Manning naked and keeping him in a cage "in order to break him".
He said Manning had not been given a fair trial.
It was a view shared by Greens Senator Scott Ludlam.
Australian Greens Senator Scott Ludlam has condemned the conviction described Manning's actions as a "public service", claiming his conviction posed a threat to a free press in the US and around the world.
"The constant cry that he and Wikileaks have blood on their hands has been proven untrue, yet this repetition has distracted attention from the actual blood of thousands of civilians in brutal wars.
"Bradley Manning has embarrassed US officials for the insecurity of their information systems, for routine and cavalier violations of the Geneva Conventions revealed in the Afghanistan War Logs and Iraq files and the hubris and poor taste of diplomats revealed through Cablegate. This is not damage; it is a public service."
"We are all in Bradley Manning's debt. He saw wrongs and did not turn away.
"With his decision to become a whistleblower, he presented some brutal and haunting truths about wars involving Australia which cannot and will not be locked away."
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