Manafort 'lied' in Russia probe

Donald Trump's former campaign chairman Paul Manafort breached his plea deal by lying to federal investigators, US prosecutors said in a court filing, signaling a potential setback to the special counsel's probe into Russia's meddling in the 2016 US presidential election.

Manafort said in the same filing on Monday that he disagreed with Special Counsel Robert Mueller's assertion that he had lied, but both sides agreed the court should move ahead and sentence him for his crimes.

Without a pardon, the 69-year-old Manafort could spend the rest of his life in prison, experts said.

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. He attended a meeting at Trump Tower in June 2016 with a group of Russians offering "dirt" on Hillary Clinton.

Manafort started cooperating in September after pleading guilty in a federal court in Washington to conspiracy against US - a charge that included a range of conduct from money laundering to unregistered lobbying. He also admitted that he tried to tamper with witnesses.