A former Wikileaks spokesman claims to have deleted thousands of unpublished files that had been passed to the whistleblowing site.Daniel Domscheit-Berg told the German Newspaper Der Spiegel that the documents included a copy of the complete US no-fly list.
He said he had "shredded" them to avoid their sources being compromised.
Mr Domscheit-Berg previously worked alongside Julian Assange until the pair had a high profile falling-out.
It is understood that he took the files off Wikileaks' servers at the time of his departure.
Wikileaks confirmed the claims on its Twitter feed, saying: "We can confirm that the DDB claimed destroyed data included a copy of the entire US no-fly list."
The list contains the names of individuals who are banned from boarding planes in the United States or bound for the US, based on suspected terrorist links or other security concerns.
Wikileaks' statement went on to state that Mr Domscheit-Berg had also deleted 5 gigabytes of data relating to Bank of America, the internal communications of 20 neo-Nazi organisations and US intercept information for "over a hundred internet companies."
Mr Domscheit-Berg has not confirmed those additional claims.
A statement, attributed to Julian Assange, accused the former volunteer of sabotage and attempted blackmail.
Personality clash Daniel Domscheit-Berg worked with Wikileaks as a spokesman during 2010. Towards the end of the year, he left the organisation.
He subsequently published a book about his experiences in which he claims to have clashed with Mr Assange over his idiosyncratic running of Wikileaks.
In an interview with the BBC's Panorama programme, Mr Domscheit-Berg said he "felt that [Wikileaks] was crumbling apart because [Julian Assange] was so damn ignorant".
He also accused Mr Assange of "behaving like a child clutching on his toy."
After his departure from Wikileaks, Mr Domscheit-Berg set up a rival whistle-blowing site called the OpenLeaks project.