Donald Trump fired back Monday at James Comey, saying he is guilty of “many crimes,” as the former FBI director opened a book tour with an interview in which he labelled the US president “morally unfit” for office.

Trump accused Comey of lying to Congress and exonerating Hillary Clinton in a 2016 investigation because of her strong poll numbers in the presidential race.

“Comey drafted the Crooked Hillary exoneration long before he talked to her (lied in Congress to Senator G),” Trump fired in an early morning tweet.

Then based his decisions on her poll numbers. Disgruntled, he, [former FBI deputy director Andrew] McCabe, and the others, committed many crimes!”

Late Sunday, Comey launched a publicity tour for his new memoir, “A Higher Loyalty: Truth, Lies and Leadership,” with an ABC television interview in which he branded Trump a serial liar who will “stain everyone around him.

Comey’s book, which leaked out last week ahead of its official release Tuesday, takes on the president who fired him in May 2017 over the troubling Russia election meddling investigation, a probe that poses a deep threat to Trump’s 15-month-old presidency.