The former manager of Donald Trump’s presidential campaign, Paul Manafort, is to face charges related to an inquiry into alleged Russian meddling, US media report.
According to a BBC report, he was seen arriving at an FBI office in Washington with his lawyer early on Monday.
An investigation headed by special counsel Robert Mueller is looking into any links between Russia and the Trump campaign during the vote.
Both sides deny any collusion.
Mr Mueller’s team is known to have conducted extensive interviews with several current and former White House officials as part of the inquiry.
One of Mr Manafort’s business associates, Rick Gates, has also been ordered to surrender to authorities, according to the reports.
The nature of the charges Mr Manafort and Mr Gates face is not yet clear.
US intelligence agencies have already concluded that the Russian government sought to help Mr Trump win the election.
But President Trump has strenuously rejected allegations of collusion, calling the investigation a “witch hunt”.