WASHINGTON — Federal prosecutors say confidential material from the Russia investigation was altered and released online as part of a disinformation campaign to discredit special counsel Robert Mueller's probe, according to a court filing Wednesday.

The material had been handed over to defense attorneys for Concord Management and Consulting LLC, a Russian company that Mueller has charged with financing efforts to meddle in the 2016 U.S. presidential election.

But the files, which prosecutors say were not sensitive, surfaced online last year in a link posted by a pro-Russian Twitter account.

The prosecutors stopped short of accusing Concord of leaking the material, but they argue that the company's request to have sensitive new evidence sent to Russia "unreasonably risks the national security interests of the United States."

Concord is controlled by Yevgeny Prigozhin, a wealthy businessman known as "Putin's chef" for his ties to Russian President Vladimir Putin. He has been hit with U.S. sanctions over Russian interference in the 2016 election and is charged alongside his company in the indictment brought by Mueller.

The company is one of three entities and 13 individuals charged in a conspiracy to spread disinformation on social media during Donald Trump's successful presidential bid. Concord is the only defendant to respond to the allegations in court, which means its attorneys have access to evidence in the case.

In Wednesday's filing, prosecutors cited a Twitter account that surfaced last year purporting to have a stolen copy of evidence provided to the company. A tweet from the account