Mr Mueller is leading the federal investigation into Russian meddling in the 2016 presidential election, and possible collusion between Trump campaign officials and Moscow - and he has accused Manafort of breaching a plea agreement by lying to FBI investigators
The prospect of new charges adds to the legal peril of Manafort, the onetime political consultant who pleading guilty to conspiracy counts in Washington DC as part of the plea deal.
US District Judge Amy Berman Jackson who is presiding over the trial has ordered Mr Mueller's team to divulge more details regarding the false-statement allegations against Manafort by 7 December.
For months Manafort, 69, had refused to work with Mr Mueller but in September made a deal to plead guilty, cooperate with investigators and forfeit million of dollars in assets, including an apartment in Trump Tower in Manhattan. The agreement came shortly before he was to have gone on trial in Washington DC on charges including money laundering, failing to register as a lobbyist for work in Ukraine and conspiracy to defraud the United States.
Manafort faces a separate sentencing early next year over a conviction from a Virginia court on eight counts of financial crimes relating to the lobbying work in Ukraine.
Prosecutor Andrew Weissmann said the Justice Department is evaluating whether Manafort could be charged over the lying allegations, or whether he could still be held liable for crimes he's admitted to but is not currently charged with in federal court.
“I don't know at this time. We will have to evaluate whether it will be fruitful to take action” on those crimes, Mr Weissmann said.
The same is true of whether they'll pursue the 10 felony counts Mr Mueller's team dismissed in Virginia or others they planned to drop in Washington as part of the plea deal, Mr Weissmann said. Jurors deadlocked on those Virginia counts and convicted Manafort on eight others.
Manafort has pushed back against the new lying allegations. His lawyers have said Manafort “believes he has provided truthful information and does not agree with the government’s characterization or that he has breached the agreement.”
As for Mr Trump, he is facing continued questions about whether he might pardon Manafort. At the same time, he is playing down the significance of the guilty plea of his former lawyer, Michael Cohen, for lying to Congress over a Trump real estate deal in Moscow.
In early morning tweets from Buenos Aires where the president is attending the G20 summit, Mr Trump said he had “lightly looked” at a real estate project “somewhere in Russia” during his presidential bid, saying it was “very legal & very cool” to do so while campaigning.
Throughout his campaign Mr Trump downplayed his Russian business interests.
Reuters contributed to this report
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