U.S. prosecutors said in court Tuesday that Lev Parnas, an associate of U.S. President Donald Trump's personal lawyer Rudy Giuliani, received a $1 million payment from a lawyer for Ukrainian oligarch Dmytro Firtash.

Prosecutors said that the Ukraine-born U.S. citizen Parnas, who has been charged with campaign finance violations, concealed the payment from them and said his bail should be revoked because he posed an "extraordinary risk" of fleeing the United States.

However, U.S. District Judge Paul Oetken in New York ruled at a hearing on Tuesday that Parnas may remain under house arrest in Florida. Parnas had not made any "clear or direct misstatement" about his finances, Oetken said.

"I feel so relieved," Parnas, who was arrested in October, said after the hearing.

Parnas was charged alongside another Florida businessman, Belarus-born Igor Fruman, with illegally funnelling money to a pro-Trump election committee and other politicians. Fruman and Parnas have pleaded not guilty.

Their case is unfolding as prosecutors investigate payments made to Giuliani, who has not been charged with a crime and has denied any wrongdoing.

Giuliani has said Parnas assisted him in investigating Joe Biden and his son, Hunter. (Shannon Stapleton/Reuters)

Giuliani has said Parnas and Fruman assisted him in investigating Trump's political rival Joe Biden and Biden's son Hunter, who served on the board of a Ukrainian energy company.

Giuliani has emerged as a key figure in the impeachment probe of Trump. Democrats have accused the Republican president of abusing his power to pressure Ukraine to investigate the Bidens. Trump has called the impeachment probe a witch hunt.

Last week, prosecutors told Oetken that Parnas had concealed information about his finances, including a $1 million payment he had received from an account in Russia in September.

The account into which the payment was deposited was in the name of Parnas's wife, Svetlana Parnas, according to court filings.

Assistant U.S. Attorney Rebekah Donaleski said in court the source of the payment was Firtash's lawyer and that it was meant for Parnas. She said it was not plausible the lawyer would extend "an unsecured, undocumented loan to a housewife with no assets."

A lawyer for Parnas, Joseph Bondy, identified Firtash's attorney as Swiss national Ralph Oswald Isenegger and said that Isenegger had asked for the money back. Bondy denied that Parnas hid the payment from prosecutors.

Reuters was unable to reach Isenegger for comment.

Firtash, one of Ukraine's wealthiest businessman, is fighting extradition by U.S. authorities on bribery charges from Vienna, where he has lived for five years.

Firtash's spokesperson could not immediately be reached for comment.

Prosecutors also said on Tuesday that Parnas had concealed $200,000 in income he earned working for Firtash's law firm, diGenova & Toensing. The firm could not immediately be reached for comment.

The firm previously said that Parnas worked as an interpreter in connection with Firtash.

Prosecutors cited Firtash as an example of Parnas's wealthy foreign connections in arguing that he was a flight risk.

Bondy denied Parnas hid the law firm income and said Parnas "has absolutely no continuing relationship with Mr. Firtash."