It was not immediately clear what new charges Manafort and Gates face. Politico reported that the charges were put under seal by the court.
Manafort and Gates were indicted in October on a dozen charges in connection to consulting work they did in Ukraine. In the 31-page indictment, federal prosecutors accused Manafort and Gates of conspiring against the United States, conspiring to launder money and working as unregistered foreign agents.
Both Manafort and Gates have pleaded not guilty.
The new charges were filed one day after an attorney pleaded guilty to lying to the FBI in the agency's investigation into Russian meddling in the 2016 presidential election and its possible ties to Trump's campaign officials.
Lawyer Alex Van Der Zwaan pleaded guilty to lying about work he did in 2012 in Ukraine, when he helped to prepare a report on the trial of former Ukrainian Prime Minister Yulia Tymoshenko. Authorities said Van Der Zwaan lied about his last contact with Gates and about communications he had with a person identified in court records only as "Person A."
He worked as an associate in the London office of Skadden, Arps, Slate, Meagher & Flom, a prominent law firm that came to the attention of the Justice Department in connection to its work in Ukraine, The New York Times reported. Manafort used Skadden to help shield one of his clients, former Ukrainian President Viktor Yanukovych, from criticism over his prosecution of Tymoshenko, according to the newspaper.
Tymoshenko was convicted of abusing her office in 2011 in a case that drew condemnation from the European Union, Reuters reported. Critics accused Yanukovych of pursuing charges against Tymoshenko for political reasons.
READ MORE: Mueller investigation: Lawyer pleads guilty to lying to investigators in Russia probe | Who is Rick Gates and why was he indicted by Robert Mueller? | Who is Paul Manafort, the man indicted in Robert Mueller's Russian investigation? | What are Paul Manafort and Rick Gates charged with? | MORE
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