WASHINGTON (AP) — An FBI informant has been charged with lying to authorities about a multimillion-dollar bribery scheme between President Joe Biden, his son Hunter and a Ukrainian energy company.

The claim is central to a Republican impeachment inquiry in Congress.

Prosecutors say Alexander Smirnov falsely told FBI agents in June 2020 that executives associated with the Ukrainian energy company Burisma paid Hunter and Joe Biden $5 million each in 2015 or 2016.

The allegations became a flashpoint in Congress over the summer as Republicans demanded the FBI release the unredacted form documenting the allegations as they pursued investigations of President Biden and his family.

They acknowledged at the time that it was unclear if they were true.