FBI counterintelligence officials were alarmed last year when a handful of Russian business leaders and activists with close ties to President Vladimir Putin showed up at Donald Trump’s inaugural festivities, the Washington Post reported Saturday.

Though the report does not specify which attendees drew of the FBI’s interest, former U.S. officials told the Post that they were concerned by the presence of individuals who had come up in the federal probe into the Trump campaign’s links to Russia.

The FBI and White House respectively declined and did not respond to the newspaper’s requests for comment.

Those in attendance included oil tycoon Viktor Vekselberg, pharmaceutical executive Alexey Repik, and lawyer Natalia Veselnitskaya. Special counsel Robert Mueller is investigating Veselnitskaya’s summer 2016 meeting at Trump Tower with Donald Trump Jr. and other key campaign officials.

According to the Post’s report, these members of Russia’s one percent rubbed shoulders with high-ranking U.S. officials at balls and other events celebrating Trump’s surprise victory.