WASHINGTON (Reuters) - A federal judge on Friday ordered lawyers for Special Counsel Robert Mueller and President Donald Trump’s former campaign chairman Paul Manafort to appear Feb. 4 for a closed hearing on whether Manafort breached his plea deal by lying to investigators.

FILE PHOTO: Former Trump campaign manager Paul Manafort arrives for arraignment on a third superseding indictment against him by Special Counsel Robert Mueller on charges of witness tampering, at U.S. District Court in Washington, U.S. June 15, 2018. REUTERS/Jonathan Ernst/File Photo

Judge Amy Berman Jackson in the U.S. District Court for the District of Columbia cast doubt on some of the lying allegations against Manafort but said others appeared more firm.

The special counsel has accused Manafort, 69, of breaching his plea deal by lying to federal investigators on at least five different subjects ranging from his contacts with Trump administration officials in 2018 to his interactions with his former business partner in Ukraine Konstantin Kilimnik, who Mueller’s office has said has ties to Russian intelligence.

Some details about Manafort’s alleged lies were made public inadvertently by his defense lawyers in a Jan. 8 court filing. Prosecutors said Manafort lied about sharing election polling data with Kilimnik, about his discussions with Kilimnik concerning a Ukrainian peace plan and a meeting the two had in Madrid.

Kilimnik, who has denied ties to Russian intelligence, was indicted by Mueller in June on obstruction of justice charges.

Manafort’s attorneys say he had memory lapses but was not trying to lead investigators astray.

Jackson said the court would release a redacted transcript of Manafort’s February hearing soon after its conclusion.

She said she was a bit torn after reading the court pleadings. Jackson said “not all of the instances rise to the level of actual false statements within the meaning of the criminal code” but that in other cases Manafort “may have lied - pure and simple.”

If Jackson finds Manafort breached his agreement, it is still unclear how it would impact his sentence.

Manafort pleaded guilty in September 2018 in the Washington case to attempted witness tapering and conspiring against the United States, a charge that covers conduct including money laundering and unregistered lobbying. Both counts carry a statutory maximum of 10 years, which is well below the sentencing guidelines.

To increase the sentence beyond the 10-year maximum, prosecutors could file fresh charges against Manafort for lying or recharge him with the other remaining counts in the indictment, according to sentencing experts.

Jackson also could consider stacking his sentence on top of whatever he gets in the Eastern District of Virginia, where he is due to be sentenced on Feb. 8 after a jury convicted him on eight counts of bank and tax fraud.

On Friday, prosecutor Andrew Weissmann said his office does not currently intend to charge Manafort with other crimes and there is no reason to delay sentencing.

He declined to rule out the chance that charges could be filed later against Manafort by Mueller’s office or other Justice Department prosecutors.

Manafort, who has in recent months waived most court appearances, showed up to court on Friday wearing a suit and walking with the assistance of a cane.

His hearing came on the same day that his former business partner and fellow Trump campaign associate Roger Stone was arrested on charges of obstruction, witness tampering and making false statements related to the release of stolen Democratic Party emails during the 2016 presidential campaign.

Mueller, a former FBI director, is investigating whether Trump’s campaign conspired with Moscow and whether the president unlawfully sought to obstruct the probe. Russia has denied election interference. Trump has denied collusion with Moscow.