The Justice Department is "likely" to file additional charges in the case against two associates of Rudy Giuliani accused of funneling foreign money to U.S. political candidates, a prosecutor said Monday.

The disclosure was made during a court hearing in New York related to the case of Lev Parnas and Igor Fruman. The federal prosecutor didn't offer any further details on the nature or target of any additional charges.

Parnas and Fruman were charged with violating campaign finance laws. They have pleaded not guilty.

The two men were carrying one-way tickets to Vienna when they were arrested at Dulles Airport outside of Washington on Oct. 9.

The indictment unsealed the next day accused Parnas and Fruman of making illegal straw donations, including $325,000 to a pro-President Donald Trump political action committee. Federal prosecutors say the two also engaged in a scheme to force the ouster of the then-U.S. ambassador in Ukraine.

The removal of the former ambassador, Marie Yovanovitch, in May is among the events House Democrats have focused on in the impeachment inquiry. Democrats accuse Trump of abusing his power by pressuring Ukraine to launch an investigation of Joe Biden, his political rival, and Biden's son.

Giuliani has acknowledged that Parnas and Fruman assisted in his effort to dig up dirt on the Bidens.

Prosecutors seized thousands of files, nine gigabytes of data, dozens of cell phones and a sat phone from Parnas, Fruman and two associates also charged in the case, David Correia and Andrey Kukushin.

Assistant U.S. Attorney Douglas Zolkin told the court Monday that Parnas has not provided the passwords to his phones despite numerous requests, and the FBI is using its technology to try and crack the phones and image the devices.

Federal prosecutors also told the judge that there were no Title III wiretaps in the case, meaning they did not eavesdrop on phone conversations prior to charging the four men.

In court Monday, Kukushkin’s attorney, Gerald Lefcourt told the court that multiple pages of search warrant affidavits provided to the defense had been completely redacted. He showed a physical copy of the warrant to the judge and asked why the defense could not see it. Prosecutors indicated that there were subjects and information contained in the affidavits pertaining to their on-going investigation of the four men that must remain secret.

Parnas and Fruman refused to cooperate in the House impeachment inquiry. But last month, Parnas' new lawyer said he was willing to speak with congressional investigators.

The lawyer, Joseph Bondy, said Parnas was told that Rep. Devin Nunes, R-Calif., the chief defender of Trump as ranking member of the House Intelligence Committee, met with Ukraine's former top prosecutor about investigating the activities of Biden and his son Hunter.

In an appearance on Fox News late last month, Nunes sidestepped a question about the allegation. "I really want to answer all of these questions, and I promise you I absolutely will come back on the show," Nunes told host Maria Bartiromo.

Nunes added: "Everybody's going to know all the facts, but I think you can understand that I can't compete by trying to debate this out with the public media when 90 percent of the media are totally corrupt."

Both sides are expected back in court on Feb. 3, 2020, at 2 p.m.