Washington (CNN) Former Trump campaign chairman Paul Manafort was ghostwriting an op-ed while out on bail last month with a Russian who has ties to the Russian intelligence service, Justice Department Special Counsel Robert Mueller's team said Monday.

In a new filing Monday afternoon, Mueller's investigators said Manafort was working on an editorial in English as late as last Thursday and that it related to his political work for Ukraine, which factored into his money-laundering and foreign lobbying criminal charges.

The filing asks for the court to revisit a bail agreement Mueller's office and Manafort's lawyers made jointly last week. The court had not yet approved a change to his $10 million unsecured bail and house arrest.

"Even if the ghostwritten op-ed were entirely accurate, fair, and balanced, it would be a violation of this Court's November 8 Order if it had been published," prosecutors wrote. "The editorial clearly was undertaken to influence the public's opinion of defendant Manafort, or else there would be no reason to seek its publication (much less for Manafort and his long-time associate to ghostwrite it in another's name)."

Manafort has pleaded not guilty to the charges. The bail agreement the lawyers appeared to have reached would have freed him from house arrest and GPS monitoring while asking him to post more than $11 million in real estate as collateral. Prosecutors have argued since his arrest October 30 that Manafort is a flight risk.

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