Special counsel Robert Mueller departs after a meeting on Capitol Hill in Washington. File picture: J. Scott Applewhite/AP

New York - This investigation has it all.

Special counsel Robert Mueller got his hands on a "nude selfie" while collecting a cache of data from a Russian company charged with interfering in the 2016 presidential election, according to a court filing.

Concord Management and Consulting, which is accused of coordinating a massive social media plot to help elect President Donald Trump, lamented in court papers late Thursday that the special counsel is overstepping his authority by refusing to release some of the data his team has obtained.

Mueller argues the data should be sealed because it contains "sensitive" information about national security and US intelligence techniques.

Concord's lawyers begged to differ.

"Could the manner in which he collected a nude selfie really threaten the national security of the United States?" the lawyers asked in the filing.

It was not clear from the filing who was portrayed in the selfie and the exotic revelation wasn't referenced at any other point in the papers.

A spokesman for the special counsel declined to comment.

Concord, which is the only Russian defendant charged in the special counsel investigation to actually engage in a US court, has pleaded not guilty to a conspiracy charge related to the Kremlin's sweeping interference in the election.

The company is owned and operated by Yevgeny Prigozhin, a billionaire oligarch who's been nicknamed "Putin's chef" because of his closeness with the Russian president.

Prigozhin, 57, has been separately indicted by Mueller with bankrolling the so-called Internet Research Agency. The Kremlin's primary troll farm launched a multifaceted interference campaign to boost Trump's chances and disparage Hillary Clinton.

Mueller continues to investigate whether the Trump campaign colluded with any Russians before the election. His inquiry has produced dozens of indictments against Trump associates and Russian nationals, including the president's former campaign chairman, national security adviser and personal lawyer.

tca/dpa