"Prosecutors say their extensive political contributions, beginning in early 2018, were created to curry favor with American policymakers in an effort to advance Parnas' and Fruman's political and business endeavors".
They were expected to appear on Thursday and Friday before Democratic-led congressional committees investigating Mr Trump.
The businessmen, Lev Parnas and Igor Fruman, were arrested in connection with a NY case involving campaign finance laws, a spokesman for the U.S. Attorney's Office in Manhattan said.
An attorney for the two men did not immediately respond to a request for comment.
The indictment filed in NY also names an American-born businessman, David Correia, and Ukraine-born Andrey Kukushkin. That could put the two men squarely in the middle of the investigation into Giuliani's activities.
Parnas and Fruman created Global Energy Producers (GEP), and allegedly funneled money through the company.
Messrs. Parnas and Fruman had dinner with the president in early May 2018, according to since-deleted Facebook posts captured in a report published by the Organized Crime and Corruption Reporting Project.More news: American Airlines pushes back return of 737 Max jets
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A spokeswoman for America First Action said the super PAC had placed the contribution in a segregated bank account following the complaint filed with the FEC. Parnas said he was not trying to hide the source of the $325,000 donation.
"We take our legal obligations seriously and scrupulously comply with the law and any suggestion otherwise is false", the statement said.
Parnas was Giuliani's fixer in Ukraine, introducing him to current and former officials as far back as 2018, according to CNN's reporting. They are my clients and I have advised them to press charges.
Parnas told Reuters last month he knew the FBI was investigating him but was not sure why. The campaign finance allegations against them are inextricably linked with that effort. Parnas and Fruman and noting that the two men had assisted Mr. Giuliani "in connection with his representation of President Trump". They four also accused of also taking steps to evade contribution limits on political donations by using straw donors.
Additionally, contributions from Fruman were allegedly made in Parnas' name to get around federal contribution limits, and several contributions were made under the name "Igor Furman" instead of "Fruman", allegedly "to hide the source of the funds and to evade federal reporting requirements".
Mr. Parnas made his first donation, of about $100,000, on October 24, 2016, to the Trump campaign and the Republican National Committee, the records show.