Washington (CNN) Former FBI Director James Comey said in an op-ed for The Washington Post that President Donald Trump tells "dumb lies" to attack the FBI and investigations of his 2016 campaign.

"Go ahead, investigate the investigators, if you must," Comey wrote. "When those investigations are over, they will find the work was done appropriately and focused only on discerning the truth of very serious allegations. There was no corruption. There was no treason. There was no attempted coup. Those are lies, and dumb lies at that. There were just good people trying to figure out what was true, under unprecedented circumstances."

Comey's statement evoked many of Trump's repeated critiques of the origin of the Russia investigation, including accusations of treason and abuse of surveillance authority.

Barr has defended the review and said it could prompt rule changes at the FBI.

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