The FBI is in possession of “voluminous evidence” of “potential criminal conduct” by President Joe Biden’s son Hunter Biden related to his overseas business dealings with China and Ukraine, according to new whistleblower disclosures.

Sen. Chuck Grassley (R-IA), who previously released whistleblower claims alleging that evidence on Hunter Biden’s criminality was wrongly labeled “disinformation” within the bureau, made the revelations in a Thursday letter obtained by the Washington Examiner. It was sent to Attorney General Merrick Garland, FBI Director Christopher Wray, and Delaware U.S. Attorney David Weiss — who is running the criminal investigation into Hunter Biden.

The whistleblower allegations relate to Hunter, as well as James Biden, the president’s brother, regarding the duo’s dealings with the Chinese government-linked energy conglomerate CEFC China Energy. They also relate to the younger Biden’s work for Ukrainian gas giant Burisma Holdings. Grassley said his staff “reviewed the unclassified records” supporting the whistleblower claims.

“Based on recent protected disclosures to my office, the FBI has within its possession significant, impactful, and voluminous evidence with respect to potential criminal conduct by Hunter Biden and James Biden,” Grassley said in the letter.