Updated April 16, 2018 15:35:10

Former FBI director James Comey has unleashed on Donald Trump in his latest television interview, describing the US President as someone who will "stain everyone around him".

Appearing on ABC News in America, Mr Comey said that was the challenge faced by the Trump administration.

"The question is, how much stain is too much stain and how much stain eventually makes you unable to accomplish your goal of protecting the country and serving the country?" he told anchor George Stephanopoulos.

He also said it was possible Russia was holding something over Mr Trump.

"These are more words I never thought I'd utter about a president of the United States, but it's possible," he said.

"I wish I wasn't saying it, but it's just — it's the truth."

Mr Comey's comments in the interview are almost certain to escalate his war of words with the president and further erode a relationship marked by open hostility and name-calling.

Hours before the interview aired, the president, who fired Mr Comey last year, unleashed a Twitter outburst that labeled Mr Comey "slippery," suggested he should be put in jail and branded him "the WORST FBI Director in history, by far!"

Mr Comey's televised remarks, coupled with the release of his forthcoming book, offer his version of events surrounding his firing and the investigations into Russian election meddling and Hillary Clinton's email practices.

Several of the episodes he describes in detail, including a private conversation about former White House national security adviser Michael Flynn, are central to special counsel Robert Mueller's investigation and his recollections could be valuable for prosecutors examining whether the president's actions constitute obstruction of justice.

'Not fit to be president'

Photo: The renewed attacks came ahead of a highly anticipated television interview with Mr Comey. (Reuters: Joshua Roberts/AP: Evan Vucci)

Mr Comey answered "possibly" when asked if the president was attempting to obstruct justice when he cleared the Oval Office of other officials last February before encouraging him to close the investigation into Mr Flynn, who by that point was suspected of lying to the FBI about his Russian contacts.

"Possibly. I mean, it's certainly some evidence of obstruction of justice," Mr Comey said.

Here's how Donald Trump's sacking of FBI director James Comey all unfolded.

The retired general pleaded guilty last December and is now cooperating with Mueller's investigation.

Mr Comey also said he believed Mr Trump was "morally unfit" to be president and that he treated women like "pieces of meat".

"A person who sees moral equivalence in Charlottesville, who talks about and treats women like they're pieces of meat, who lies constantly about matters big and small and insists the American people believe it — that person's not fit to be president of the United States, on moral grounds," he said.

Mr Comey is currently promoting his new tell-all book, A Higher Loyalty, which is reportedly very critical of Mr Trump.

In the book, due to be released later this week, Mr Comey compares Mr Trump to a mafia don and calls his leadership of the country, "ego driven and about personal loyalty".

In an excerpt shown on Saturday, Mr Comey said his belief Mrs Clinton would beat Mr Trump in the 2016 presidential election was a factor in his decision to disclose the investigation into her emails.

Mr Trump seized on that, saying Mr Comey, "was making decisions based on the fact that he thought she was going to win, and he wanted a job. Slimeball!"

He also suggested Mr Comey should be imprisoned, saying: "How come he gave up Classified Information (jail), why did he lie to Congress (jail)."

There is no indication Mr Comey is under investigation for doing either.

Asked if the president wanted the Justice Department to investigate Mr Comey, White House spokeswoman Sarah Huckabee Sanders said she was not aware of a specific request.

But, she said, "if they feel there was any wrongdoing, they should certainly look into that just as they do on a number of other topics".

Asked whether he believed Mr Trump should be impeached, Mr Comey replied, "I hope not because I think impeaching and removing Donald Trump from office would let the American people off the hook and have something happen indirectly that I believe they're duty bound to do directly."

"People in this country need to stand up and go to the voting booth and vote their values."

ABC/AP

Topics: government-and-politics, world-politics, donald-trump, united-states

First posted April 16, 2018 12:51:30