PRESIDENT Donald Trump has bemoaned his country’s “very weak” libel laws, saying he is “like, really smart” and, indeed, a “very stable genius”.

His defence of his mental fitness in a series of tweets, following coverage in a new book, was a singular episode in a presidency rife with moments unlike any that have come before in that office.

He was criticising Fire And Fury: Inside The Trump White House, which paints him as a leader who does not understand the weight of his office and whose competence is questioned by aides.

“Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart,” Trump tweeted from Camp David, the presidential retreat in Maryland, a few hours before a strategy session on the 2018 legislative agenda with Republican congressional leaders and Cabinet members.

His ire was directed at author Michael Wolff, whose book draws a derogatory portrait of the 45th president as an undisciplined man-child who did not actually want to win the White House and who spends his evenings eating cheeseburgers in bed, watching television and talking on the telephone to old friends.

“I consider it a work of fiction,” Trump told reporters. “The libel laws are very weak in this country.