Domscheit-Berg, estranged German cohort of Julian Assange, told Der Spiegel magazine that he "shredded" the files only recently to ensure no sources would be compromised.
Among the information said to be lost forever are the US government's “no-fly” list, which lists people not allowed to board US aircraft, as well as inside information from 20 far-right extremist organizations.
Wikileaks and its leader Assange responded furiously to Domscheit-Berg's announcement. In a written statement, the organization accused him of “blackmail” and said Domscheit-Berg had threatened to make the documents available to “forces that oppose WikiLeaks.”
The group said it had attempted to negotiate with Domscheit-Berg through a mediator but those efforts had failed.
Meanwhile, a release from Assange attacked Domscheit-Berg and accused him and his wife of having contact with intelligence agencies.
Domscheit-Berg has been a controversial figure for quite some time. He left WikiLeaks after being suspended by the group in 2010 after Assange said his stability and reliability came into question. His book, “Inside WikiLeaks” criticized Assange as mercurial and unreliable.
He has recently launched his own leak website called OpenLeaks, but was kicked out of the hacker group the Computer Chaos Club for allegedly exploiting the group's name.
"He wants to use us as a credibility voucher," said the CCC's Andy Müller-Maguhn, a friend of Assange who had tried to mediate with Domscheit-Berg over the return of the now destroyed documents.