WASHINGTON, Feb. 23 (Xinhua) -- New charges were filed late Friday against former Trump campaign chairman Paul Manafort in the Russia probe led by special counsel Robert Mueller.

Prosecutors alleged that Manafort, with the help of his longtime business associate, Rick Gates, secretly paid former senior European politicians in 2012 and 2013 to lobby for the pro-Russia government of Ukraine.

The superseding indictment said Manafort used offshore accounts to wire more than 2 million euros (about 2.5 million U.S. dollars) to the unnamed former politicians.

The new indictment came hours after Gates, also a former Trump campaign aide, pleaded guilty to charges of conspiracy against the United States and making false statements to the Federal Bureau of Investigation (FBI).

Gates pledged to cooperate with Mueller in the ongoing Russia probe into alleged collusion between the Trump campaign and Russia and Russian meddling in the 2016 U.S. presidential elections.

The latest charges against Manafort and Gates' plea came a day after a new indictment against the pair included additional charges of tax evasion and bank fraud.

They were charged last October with money laundering, conspiracy and other offenses in a federal court in Washington. Manafort has pleaded not guilty to all charges against him.

In a statement prior to Friday's indictment, Manafort said he continues to maintain his "innocence" and Gates' plea would not alter his commitment to defending himself against "the untrue piled up charges."