Former FBI director James Comey pleaded not guilty on Wednesday to felony charges in a case widely seen as an escalation of US President Donald Trump's campaign of retribution against political opponents.

Comey, 64, a prominent critic of the president, was indicted by a grand jury last month on charges of making false statements to Congress and obstructing a congressional proceeding.

Comey's lawyer, Patrick Fitzgerald, entered a not guilty plea before District Judge Michael Nachmanoff during his arraignment at a federal courthouse in Alexandria, Virginia.

The judge set a trial date of January 5.

A few protestors had gathered outside the court ahead of Comey's arrival, including a man holding up a sign reading "Show Trial."

Comey's indictment stems from sworn testimony he gave to the Senate Judiciary Committee in 2020.

He is accused of falsely stating that he had not authorised another FBI employee to be an anonymous source in news reports.

He faces up to five years in prison if convicted.

Comey was appointed to head the FBI by president Barack Obama in 2013 and was fired by Trump in 2017 amid a probe into whether any members of the Trump presidential campaign had colluded with Moscow to sway the 2016 vote.

The charges against Comey came just days after Trump had publicly urged Attorney General Pam Bondi to take action against the former FBI director and others he sees as enemies – a stunning departure from the principle that the Justice Department must be free from White House pressure.

The 79-year-old Trump – the first convicted felon to serve as US president – hailed the indictment, calling Comey "one of the worst human beings this country has ever been exposed to." (AFP)