Special Counsel Robert Mueller wants President Donald Trump’s former campaign manager Paul Manafort to be put in jail while he awaits trial because he allegedly tampered with witnesses.

Mueller filed a motion in federal court asking a judge to revoke Manafort’s $10m bail, according to The New York Times.

Manafort has been indicted for financial crimes related to his work as a lobbyist for foreign actors.

Special Counsel Robert Mueller wants President Donald Trump’s former campaign manager Paul Manafort (above) to be put in jail while he awaits trial because he allegedly tampered with witnesses

Manafort was Trump's (above) campaign manager during a crucial stretch of the 2016 campaign

Prosecutors working with Mueller say that Manafort tried to contact witnesses in the case using an encrypted messaging program on his cell phone.

Manafort allegedly sent numerous text messages to a potential witness using WhatsApp.

The messages allegedly sent on WhatsApp were then backed up on Manafort's iCloud, according to prosecutors.

Mueller is now asking a judge to either revise the terms of his release or revoke it entirely, which could mean he will have to stay in jail until his trial.

In court papers, the FBI is alleging that at least one witness in the Manafort case was contacted by the former Trump aide and coached on what he should say about his lobbying practices.

The court filings are available here.

Prosecutors working with Mueller say that Manafort tried to contact witnesses in the case using an encrypted messaging program on his cell phone

FBI Special Agent Brock Domin, in a declaration filed with Mueller’s motion, said Manafort had attempted to call, text and send encrypted messages in February to two people from The Hapsburg Group, a firm he worked with to promote the interests of Ukraine.

The FBI has documents and statements from the two people, as well as telephone records and documents recovered through a search of Manafort’s iCloud account showing that Trump’s former campaign manager attempted communication while he was out on bail, according to Domin.

The communications were 'in an effort to influence their testimony and to otherwise conceal evidence,' Domin wrote.

'The investigation into this matter is ongoing.'

Manafort is the most senior member of Trump’s campaign to be indicted, though the charges do not relate to campaign activities.

Mueller urged Judge Amy Berman Jackson to 'promptly' schedule a hearing on the whether to change Manafort’s conditions of release, which could result in Manafort going to jail.

The Washington trial is set to start on Sept. 17.

Trump has denied collusion with Russia and called Mueller’s investigation a 'witch hunt.'