Prosecutors have said that Parnas, who has been charged with campaign finance violations, should have his bail revoked because he concealed the payment from them. Parnas has denied hiding the payment.

The Ukraine-born US citizen was released on bail after his arrest in October and has been living under house arrest in Florida.

Last week, prosecutors asked US District Judge Paul Oetken in Manhattan to revoke Parnas’ bail.

They said he had concealed information about his finances, including a US$1 million payment he had received from an account in Russia in September.

The account was in the name of his wife, Svetlana Parnas.

On Tuesday, US Attorney Rebekah Donaleski said that the source of the payment was Firtash’s lawyer.

She said it was not plausible the payment was a loan to Parnas’s wife, as he had said.