Klyushin, who has ties to the Kremlin, was sentenced on Sept. 7 to nine years in prison after being found guilty in February of trading shares using hacked secret earnings information about multiple companies.

Hackers from 2018 to 2020 viewed and downloaded yet-to-be-announced earnings reports for hundreds of companies including Tesla and Microsoft, whose shares Klyushin and others then traded before the news was public, according to prosecutors.

Russia's Foreign Ministry said the charges against Klyushin, the owner of a Moscow-based information technology company called M-13 that did work for the Russian government, were completely far-fetched and fabricated", according to RIA.

It said he was "another victim of the fanatical Russophobia that now reigns in the power structures overseas".

"We will continue to demand that U.S. authorities put a stop to legal arbitrariness against Russian citizens," the ministry said, according to RIA.

(Reporting by Reuters; Editing by Kevin Liffey)