U.S. President Donald Trump's former national security adviser Michael Flynn lied to the FBI about his contacts with Russia's ambassador to the United States, the U.S. special counsel's office charged in a court filing made public on Friday.

The Office of the Special Counsel said a plea hearing for Flynn had been set for 10:30 a.m. EST (1530 GMT) on Friday. The Justice Department announced that the hearing will take place before U.S. District Judge Rudolph Contreras at a D.C. federal courthouse.

Then released court documents showed that Flynn has been charged with a single count of "willfully and knowingly" making false statements to the FBI on Jan. 24.

Prosecutors with the office of Special Counsel Robert Mueller say Flynn falsely stated to the FBI that he had not discussed sanctions with the then-Russian ambassador to the United States.

Flynn is the fourth person charged in connection with Mueller's investigation.