Special Counsel Robert Mueller accused Paul Manafort on Monday night of violating his plea deal by lying to investigators – a move that could potentially lead to more jail time for the former Donald Trump campaign chairman.

Mueller’s team said Manafort, who was convicted earlier this year on multiple counts of financial fraud in connection to his work as a political consultant in Ukraine, “committed federal crimes” by lying to Mueller’s team and the FBI about a “variety of subject matters.”

Manafort had been meeting with the special counsel’s office since he pleaded guilty in September to conspiracy against the U.S. and conspiracy to obstruct justice. He cut that deal to head off a second trial after being convicted of eight felony counts related to millions of dollars he hid from the IRS in offshore accounts.

The plea agreement said Manafort “must at all times give complete, truthful and accurate information and testimony, and must not commit or attempt to commit, any further crimes.” It said he must “cooperate fully, truthfully, completely and forthrightly” with anything the government deems “relevant,” which could include more about his Ukranian work or the Trump campaign.

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In return, prosecutors agreed not to bring additional charges against him and to ask a judge for a reduction of his sentence if he provided “substantial assistance.”

But with prosecutors saying he breached the agreement, Manafort now faces serious repercussions such as the possibility of prosecution on additional charges, including the 10 felony counts dropped when he made the deal.

He already faces up to five years in prison on the charges in his plea agreement. In a separate case, his potential sentencing under federal guidelines has not yet been calculated, but prosecutors previously said he could spend up to 10 years in jail.

Absent a presidential pardon, Manafort, 69, could end up spending the rest of his life in prison, Reuters reported.

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Monday’s court filing did not go into detail about what exactly Manafort allegedly lied about, and the special counsel said it would submit a more detailed sentencing submission that “sets forth the nature of the defendant’s crimes and lies, including those after signing the plea agreement” at a later date.

Manafort’s team, however, said he “believes he has provided truthful information and does not agree with the government’s characterization or that he has breached the agreement.”

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The demise of the plea deal does not necessarily bode well for Mueller’s team either. According to Reuters, the special counsel could have lost an important witness in Manafort given his deep connections with the Trump campaign.

Trump has repeatedly derided Mueller’s investigation as a “witch hunt” and called the 74-year-old a “conflicted prosecutor gone rogue” Tuesday morning. On the other hand, he’s called Manafort a “brave man.”

Fox News' Matt Richardson and The Associated Press contributed to this report.