(Reuters) - A Russian national pleaded guilty on Wednesday to U.S. charges that he lied to the FBI about his participation in an organization that prosecutors said was controlled by sanctioned Russian businessman Konstantin Malofeyev.

Federal prosecutors in Manhattan said Tomas Ianchauskas, a U.S. green card holder who principally resides in Russia, served as the regional leader of the Tsargrad Society, formerly known as the Double Headed Eagle Society.

Ianchauskas, 39, pleaded guilty to one count of making false statements to FBI agents. He faces up to six months in prison under federal sentencing guidelines, according to his plea agreement, and is set to be sentenced July 11.

His lawyer did not respond to a request for comment.

The U.S. Department of the Treasury's Office of Foreign Assets Control in April 2022 imposed sanctions on that organization and other Malofeyev-led entities following Russia's invasion of Ukraine that February.

The Treasury Department described the Tsargrad Society as a group that advocates for Russia's return to a monarchical system of government and that supports "returning the Russian Empire to its historical borders," including Ukraine.

Prosecutors said the group was part an influence ecosystem led by Malofeyev, the owner of Christian Orthodox television channel Tsargrad TV, who U.S. authorities accuse of financing separatists in Crimea, which Russia annexed in 2014.

Malofeyev, who has denied financing separatists, was sanctioned by Washington in 2014 and charged by the U.S. prosecutors with sanctions violations in 2022. He could not be reached for comment and is believed to be at large in Russia.

Prosecutors said that in January 2022, FBI agents interviewed Ianchauskas at John F. Kennedy International Airport in New York before a scheduled flight and asked him about his role with the Tsargrad Society.

During that interview, he falsely stated he had not been involved with the organization for three years and had never held a leadership position with it, according to charging documents.

Prosecutors said that was a lie and that Ianchauskas served as the head of the Penza regional branch of the organization.

His membership continued after that initial FBI encounter, and Ianchauskas reiterated that he never belonged to it when he again was interviewed in December 2023, prosecutors said. He was subsequently arrested in January.

(Reporting by Nate Raymond in Boston; Editing by Bill Berkrot)

By Nate Raymond