The Blood and Honour organization has been banned in Germany since 2000, but links to around 500 Germans were found on the group's server, said the hackers on Friday.
The “Daten-Antifa” group told the Frankfurter Rundschau newspaper that it had taken a “carefully planned cloak and dagger operation” to crack the Blood and Honour network's members-only, password-protected area.
They hope to prove links between legal far right extremists such as NPD members and the illegal Blood and Honour group.
They also took the “Red-Watch” list, on which the Blood and Honour registers their political opponents, recording names and addresses.
It has so far been difficult to prove that Blood and Honour has continued to operate in Germany, Günther Hoffmann from the Centre for Democratic Culture told the paper.
“It would of course be a huge hit on the organized far right scene if it were proven that the German Blood and Honour division still existed.”