President Donald Trump has again called former FBI director James Comey a “slimeball” ahead of the publication of his new book.

Mr Trump’s morning tweet comes before Mr Comey’s interview with ABC to be broadcast in full on Sunday evening.

In an excerpt shown on Saturday, Mr Comey says his belief that Hillary Clinton would win the 2016 presidential election was a factor in his decision to disclose the investigation into her emails.

In his tweet, Mr Trump says: “Unbelievably, James Comey states that Polls, where Crooked Hillary was leading, were a factor in the handling (stupidly) of the Clinton Email probe. In other words, he was making decisions based on the fact that he thought she was going to win, and he wanted a job. Slimeball!”

The president had called Mr Comey an “untruthful slime ball” on Friday, after details first emerged of the memoir.

Mr Trump then added to his attacks on Mr Comey in a series of further tweets on Sunday.

He said: “The big questions in Comey’s badly reviewed book aren’t answered like, how come he gave up Classified Information (jail), why did he lie to Congress (jail), why did the DNC refuse to give Server to the FBI (why didn’t they TAKE it), why the phony memos, McCabe’s $700,000 & more?”

The president then tweeted: “I never asked Comey for Personal Loyalty. I hardly even knew this guy. Just another of his many lies. His “memos” are self serving and FAKE!”

And he then tweeted: “Slippery James Comey, a man who always ends up badly and out of whack (he is not smart!), will go down as the WORST FBI Director in history, by far!”

Mr Comey’s book, A Higher Loyalty, says Mr Trump is “untethered to truth”, and describes him as fixated in the early days of his presidency on having the FBI debunk salacious rumours he said were untrue but that could distress his wife.

In the book, Mr Comey compares Mr Trump to a mafia don and calls his leadership of the country “ego driven and about personal loyalty”.

He also reveals new details about his interactions with Mr Trump and his own decision-making in handling the Hillary Clinton email investigation before the 2016 election.

He casts Mr Trump as a mobster-like figure who sought to blur the line between law enforcement and politics and tried to pressure him personally regarding his investigation into Russian election interference.