Special counsel investigating Russian meddling in 2016 US election says Trump’s former campaign aide lied to FBI.

US President Donald Trump’s former campaign manager Paul Manafort has been accused of breaching a plea deal by lying to federal prosecutors, signalling a potential setback to the special counsel’s probe into Russia’s meddling in the 2016 presidential election.

In a court filing on Monday, lawyers working on Special Counsel Robert Mueller’s investigation into the alleged Russian interference said Manafort had nullified their agreement to cooperate – charges denied by the 69-year-old.

In the latest filing, Mueller’s team said Manafort “committed federal crimes” by lying about “a variety of subject matters” even after he agreed to truthfully cooperate with the investigation, which has been ongoing since 2017.

Prosecutors said they will detail the “nature of the defendant’s crimes and lies” in writing at a later date to the judge.

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Manafort, who pleaded guilty in September, denied lying and breaching his plea agreement, saying he “believes he provided truthful information” during a series of sessions with Mueller’s investigators.

But both sides agreed the court should move ahead and sentence him for his crimes.

The surprise development comes at a critical time for Mueller, who is expected to finalise a report in the coming months on the findings of his 18-month probe into Russia’s election meddling and possible collusion with the Trump campaign.

While not a fatal blow, the dissolution of Manafort’s plea agreement means Mueller is losing the contributions of a witness with deep ties to Russia and who ran the Trump campaign as it took off in mid-2016.

“It’s bad for the overall Mueller investigation,” Patrick Cotter, a criminal defence lawyer in Chicago and former assistant US attorney in New York, told Reuters news agency. “He’s got one less witness today.”

Ethical line

Manafort, who remains jailed, had been meeting with the special counsel’s office since he pleaded guilty in September to a conspiracy against the United States – a charge that included a range of conduct from money laundering to unregistered lobbying. He also admitted that he tried to tamper with witnesses.

He cut that deal to head off a second trial after being convicted last summer of eight felony counts related to millions of dollars he hid from the Internal Revenue Service (IRS) in offshore accounts.

Manafort already faces up to five years in prison on the two charges in his plea agreement. In his separate Virginia case, Manafort’s potential sentencing under federal guidelines has not yet been calculated, but prosecutors have previously said he could face as much as 10 years in prison on those charges.

Manafort was a long-time Republican political consultant who made tens of millions of dollars working for pro-Kremlin politicians in Ukraine before joining the Trump campaign in March 2016, promising to work for free.

Manafort attended a meeting at Trump Tower in June 2016 with a group of Russians offering “dirt” on Democratic candidate Hillary Clinton, who lost in an upset to Trump in the vote that November.

His long-standing relationship with an oligarch close to Russian President Vladimir Putin was another reason Manafort’s cooperation was seen as important to Mueller’s probe.

Manafort’s lawyers said he met the government on several occasions and made “an effort to live up to his cooperation obligations,” according to Monday’s joint filing, which was submitted to US District Judge Amy Berman Jackson in Washington.

Rudy Giuliani, who represents Trump in the Russia probe, said Mueller’s team had crossed an ethical line between the search for the truth and exerting too much pressure on Manafort.

“They are trying not to get a witness to sing, but to compose,” he said in an interview with Reuters on Monday night.

Mueller, a lawyer and the head of the FBI from 2001 to 2003, was appointed as special counsel to the US Justice Department to investigate possible Russian meddling in the 2016 US presidential election on May 17.