Special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE said in a court filing on Monday that President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE's former campaign chairman Paul Manafort Paul John ManafortOur Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam Conspicuous by their absence from the Republican Convention MORE has attempted to tamper with potential witnesses while on pretrial release.

Mueller's team has asked the court to revoke or revise Manafort's release conditions, including his bond and house arrest, in the wake of the filing, which was first reported by Reuters.

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FBI agent Brock Domin said in the filing that Manafort and a longtime associate linked to Russian intelligence attempted to contact via phone call, text and encrypted messages two people from the "Hapsburg group," which Manafort had worked with to lobby for Ukrainian interests.

Domin said that Manfort's attempts at contact were “in an effort to influence their testimony and to otherwise conceal evidence” and that the probe into the matter was still ongoing.

Domin said he believed the effort was an attempt to "suborn perjury."

In a Tuesday statement, Manafort's representation said the filing would not alter his defense.

"Mr. Manafort is innocent and nothing about this latest allegation changes our defense. We will do our talking in court," his attorneys said.

Mueller's investigation into Moscow's meddling in the 2016 presidential election and any possible coordination with the Trump campaign reached its anniversary last month.

The special counsel's office hit Manafort with a 12-count indictment last year, which included conspiracy against the United States, tax fraud and money laundering.

Manafort has pleaded not guilty to the charges, which are not directly related to his work for the Trump campaign.

His former business associate, Richard Gates, pleaded guilty to one count of conspiracy against the United States and one count of making a false statement to the FBI agents investigating Russian interference earlier this year as part of a plea deal with Mueller's team.

Former national security adviser Michael Flynn, former Trump campaign adviser George PapadopoulosGeorge Demetrios PapadopoulosTale of two FBI cases: Clinton got warned, Trump got investigated Trump says he would consider pardons for those implicated in Mueller investigation New FBI document confirms the Trump campaign was investigated without justification MORE and Dutch attorney Alex van der Zwaan have all also pleaded guilty in the case.

A grand jury also indicted 13 Russian nationals and three Russian entities earlier this year for allegedly meddling in the 2016 presidential election.

Manafort's former son-in-law, who is reportedly intimately familiar with his business dealings, also reached a plea deal with federal prosecutors last month.

Trump has spoken out about Manafort in recent days, slamming the FBI and Department of Justice for not telling him that agents were “secretly investigating" Manafort during the 2016 presidential race.

As only one of two people left who could become President, why wouldn’t the FBI or Department of “Justice” have told me that they were secretly investigating Paul Manafort (on charges that were 10 years old and had been previously dropped) during my campaign? Should have told me! — Donald J. Trump (@realDonaldTrump) June 3, 2018

Trump sought to distance himself from Manafort in a subsequent tweet, saying that Manafort was only with the campaign for a short period of time.

....Paul Manafort came into the campaign very late and was with us for a short period of time (he represented Ronald Reagan, Bob Dole & many others over the years), but we should have been told that Comey and the boys were doing a number on him, and he wouldn’t have been hired! — Donald J. Trump (@realDonaldTrump) June 3, 2018

—Updated Tuesday at 1:01 p.m.