The United States tightened sanctions on Monday against an ally of Russian President Vladimir Putin previously accused of trying to meddle in the 2016 presidential election, saying he had also tried to intervene in the mid-term elections last year.

Evgeny Prigozhin was indicted in Special Counsel Robert Mueller's investigation of Russian interference in the 2016 vote, accused of being a mastermind of the Internet Research Agency, a "troll farm" that tried to help elect President Donald Trump, Reuters wrote.

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In its announcement Monday, the U.S. Treasury Department said it was imposing new restrictions on Prigozhin's assets, including a yacht and several private jets, because he also attempted to meddle in the U.S. midterm elections in 2018.

The Treasury said there was no indication Prigozhin was successful at compromising any election infrastructure to prevent voting or impact vote counts, despite his attempts.

Prigozhin, sometimes described in Russian media as "Putin's chef" because of a catering business that organized banquets for Putin and other senior political figures, was accused by prosecutors in Mueller's office of controlling Concord Management and Consulting LLC, a firm that helped oversee the activities of a propaganda campaign to help Trump.

Attorneys for Concord have denied any wrongdoing and are seeking to have the criminal charges dismissed.

In addition, the Treasury said it was imposing sanctions on six members of the Internet Research Agency: Dzheykhun Nasimi Ogly Aslanov, Mikhail Leonidovich Burchik, Vadim Vladimirovich Podkopaev, Vladimir Dmitriyevich Venkov, Igor Vladimirovich Nesterov, and Denis Igorevich Kuzmin.