UPDATE 9-Giuliani associates charged with illegally funneling cash to pro-Trump group

(Adds Axios reporting U.S. ambassador to EU expected to testify, paragraphs 29-30)

By Aram Roston, Brendan Pierson and Karen Freifeld

WASHINGTON/NEW YORK, Oct 10 (Reuters) - Two foreign-born Florida businessmen who have helped President Donald Trump's personal lawyer Rudy Giuliani investigate political rival Joe Biden were arrested in a scheme to illegally funnel money to a pro-Trump election committee and other U.S. political candidates, prosecutors said on Thursday.

The arrest of Ukraine-born Lev Parnas and Belarus-born Igor Fruman at an airport outside Washington carrying one-way tickets to Vienna was the latest dramatic development in a political saga that threatens Trump's presidency.

Prosecutors said Parnas and Fruman conspired to contribute foreign money including at least $1 million from an unidentified Russian businessman to candidates for federal and state offices to buy influence.

Prosecutors separately said they donated $325,000 to a pro-Trump political action committee called America First Action in May 2018, and the money was falsely reported as coming from a purported natural gas company set up to conceal its true source, according to the indictment.

A fast-moving Democratic-led House of Representatives impeachment inquiry is centered on the Republican president's request in a July phone call for Ukrainian President Volodymyr Zelenskiy to investigate Biden, the former vice president and a top contender for the 2020 Democratic presidential nomination.

Democrats have accused Trump of pressuring a vulnerable foreign ally to dig up dirt on a domestic political opponent for his own political benefit.

Trump has denied wrongdoing and has described the impeachment probe as a partisan smear.

Giuliani has said Parnas and Fruman helped his efforts in Ukraine to investigate Biden and Biden's son Hunter. The younger Biden had served as a director of a Ukrainian energy company.

The two men were each charged by federal prosecutors in New York with two counts of conspiracy, one count of false statements and one of falsification of business records. U.S. law prohibits foreign donations in American elections.

Parnas and Fruman were trying to buy political influence to help set up recreational marijuana businesses, prosecutors said. They also said Parnas played a role in a successful effort to have Trump remove the U.S. ambassador to Ukraine.

"Protecting the integrity of our elections, and protecting our elections from unlawful foreign influence, are core functions of our campaign finance laws," U.S. Attorney Geoffrey Berman told reporters in New York. "And as this office has made clear, we will not hesitate to investigate and prosecute those who engage in criminal conduct that draws into question the integrity of our political process."