U.S. federal prosecutors are planning to interview Andrew Favorov, an executive of the Ukrainian state-owned Naftogaz oil and gas conglomerate, as part of an investigation into the business dealings of Rudy Giuliani and two of his Soviet-born business associates.

A lawyer for Favorov confirmed to AP on November 19 that the dual Ukrainian-U.S. citizen is scheduled to meet voluntarily with prosecutors.

Favorov has since November 2018 headed the integrated gas division of Naftogaz, responsible for natural-gas production, and the wholesale and retail sale of gas.

The lawyer, Lanny Breuer, declined to say when or where Favorov would be interviewed.

The Justice Department is investigating Giuliani, President Donald Trump's personal attorney, for possible campaign-finance violations and a failure to register as a foreign agent as part of its probe.

Giuliani's close associates Lev Parnas and Igor Fruman have been indicted on charges of federal campaign-finance violations, conspiracy, making false statement, and falsification of records.

They and Giuliani have been involved in back-channel meetings with current and former Ukrainian officials regarding investigations into former Vice President Joe Biden, his son Hunter, and Democratic Party activities in the 2016 presidential election.

In March, Parnas and Fruman approached Favorov at an energy conference in Texas to offer a partnership in a venture to export U.S. liquefied gas to Ukraine. They also discussed the possibility of Favorov replacing his ultimate superior, Naftogaz CEO Andriy Kobolyev.

Giuliani has denied taking part in the two suspects' efforts to seal a gas deal in Ukraine.

Before joining Naftogaz, Favorov was a managing partner and director of Energy Resources of Ukraine. A graduate of Georgetown University in Washington, Favorov was in 2010-14 the commercial director of the DTEK energy holding owned by billionaire Rinat Akhmetov.

With reporting by Fortune and AP

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