WikiLeaks founder Julian Assange has claimed that his website holds more US classified documents which are yet to be published online.
The website will, however, not release this material during the court martial of its source, US Army Private Bradley Manning, according to a report by The Age on Tuesday.
Assange, currently holed up in Ecuadorian embassy in London, described Manning as "America's foremost political prisoner… an activist who faces retribution for revealing the truth".
"Bradley Manning's plea was a very positive development for him. For the first time he was able to speak about his motivation to reveal truths and stimulate public debate about war", he said.
Assange has confirmed to the Fairfax publication that WikiLeaks had received classified material from Manning that related to a February 2010 incident in which the US military had turned a blind eye to Baghdad police arrests and persecution of political opponents of Iraqi Prime Minister Nouri al-Maliki.
Assange said that WikiLeaks had decided not to publish the material at the time for "source-protection reasons" given that the person providing the material appeared to have been connected with the US military's handling of the incident.
"We still can't publish it. It would be a questionable action to do so now while Bradley Manning has a potential life sentence hanging over his head," he said.
He said he "wouldn't go beyond what Manning has said" and "can't answer" whether the two published CIA documents were the documents referred to by Manning or whether WikiLeaks holds other intelligence agency material not yet published.
"I can't say anything that might suggest that someone had been responsible for, or was party to, any further disclosure," the 41-year-old Australian national said.
Assange confirmed that WikiLeaks received videos and other documents relating to a May 2009 US air strike near Granai village in Afghanistan that killed between 90 to 150 Afghan civilians, including many children.
The Granai air strike material ‘documented a massacre, a war crime’, he said and disputed previous media reports claiming WikiLeaks had been unable to open the encrypted video files.
"WikiLeaks obtained this material and scheduled it for release, but the opportunity to reveal these important records was lost when Daniel Domscheit Berg left WikiLeaks, taking this and other material with him, which he has said he later destroyed.
"WikiLeaks no longer has a copy," Assange said.
The hacker-turned activist is trying to avoid extradition from Britain to Sweden over allegations of rape and sexual assault in August 2010 and has been inside the Ecuadorian embassy in London since June 19, 2012 where he has been granted diplomatic asylum.