Washington: US Special Counsel Robert Mueller's office said on Wednesday that self-proclaimed hackers in Russia stole evidence prosecutors had turned over confidentially to a Russian firm accused of funding a propaganda campaign to interfere in the 2016 US election.

Special Counsel Robert Mueller. Credit:AP

Some non-sensitive data was posted online in October by a Twitter account that took credit for stealing the information, Mueller's office said in a court filing.

"We’ve got access to the Special Counsel Mueller’s probe database as we hacked Russian server with info from the Russian troll case," the court document quoted the Twitter post as saying.

The data that appeared online was "altered and disseminated as part of a disinformation campaign aimed (apparently) at discrediting ongoing investigations into Russian interference in the U.S. political system," prosecutors wrote.