Former FBI director James Comey criticized US President Donald Trump, accusing him of being unethical and relentless liar, CNN reported.

In his new book Comey painted Trump as a relentless liar who is obsessively unethical, devoid of humanity and a slave to his ego, who is clueless about his job and unconcerned about a Russian assault on American democracy.

Jabbing the President in a strikingly personal way, Comey noted the size of Trump's hands, said his skin looked orange and described white rings around his eyes from tanning goggles.

According to CNN, "Comey isn't just out to hurt Trump's feelings. He is on a more profound mission: His book is a parable about the threat from a brazen President who demands a warped concept of loyalty and has only disdain for the rule of law."

In one staggering part of the book, "A Higher Loyalty," Comey said dealing with Trump reminded him of his days prosecuting Mafia kingpins with their "silent circle of assent."

"The boss in complete control. The loyalty oaths. The us-versus-them worldview. The lying about all things, large and small, in service to some code of loyalty that put the organization above morality and above the truth."