Washington (CNN) New charges were filed late Friday against former Trump campaign chairman Paul Manafort in the special counsel investigation.

Prosecutors allege that Manafort, with the assistance of longtime business partner Rick Gates, "secretly retained a group of former senior European politicians to take positions favorable to Ukraine, including by lobbying in the United States."

The new indictment came less than two hours after Gates pleaded guilty to two criminal charges in federal court and pledged to cooperate with special counsel Robert Mueller's investigation of Russia and the 2016 presidential election.

Prosecutors say Manafort orchestrated a group of former European politicians, called the "Hapsburg group," to pose as independent voices. Yet they covertly pushed positions favorable to Ukraine as paid lobbyists. Manafort used offshore accounts to pay the former politicians 2 million euros.

Manafort also allegedly used $4 million from an offshore account to fund a report on the trial of a political opponent jailed by his clients. A lawyer involved in the report -- Alex van der Zwaan -- pleaded guilty to lying to investigators earlier this week.

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