President Donald Trump blasted James Comey as a "LEAKER & LIAR" and an "untruthful slime ball" in a pair of tweets Friday morning, and said that the former FBI director should be prosecuted for allegedly leaking classified information to news media.

"Virtually everyone in Washington thought he should be fired for the terrible job he did — until he was, in fact, fired. He leaked CLASSIFIED information, for which he should be prosecuted. He lied to Congress under OATH," the president tweeted.

"He is a weak and untruthful slime ball who was, as time has proven, a terrible Director of the FBI. His handling of the Crooked Hillary Clinton case, and the events surrounding it, will go down as one of the worst 'botch jobs' of history. It was my great honor to fire James Comey!" he added.

Trump's tweets come a day after excerpts from Comey's forthcoming tell-all paint a devastating picture of the president as an "unethical" man "untethered to truth and institutional values" who lives in "a cocoon of alternative reality."

In the book, "A Higher Loyalty: Truth, Lies and Leadership," which NBC News obtained on Thursday ahead of its scheduled release next week, Comey recounts his encounters and disagreements with Trump, who fired him on May 9.

His firing ultimately led to the Justice Department's appointment of a special counsel to probe Russia's meddling in the 2016 election and possible collusion with Trump's campaign.

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Senior White House aides, as well as the Republican National Committee, also hit back at Comey Friday.

Kellyanne Conway, counselor to the president, called Comey a "disgruntled ex-employee" who is hyping the number of times he met with the president and using it to peddle his memoir.

"He is taking one or two or three meetings with the president and retroactively putting his own spin on them to sell books," she told Fox News on Friday. "It seems to me he seems like a disgruntled ex-employee who after the fact wants to clear his conscious of what bothered him at that time."

White House Press Secretary Sarah Huckabee Sanders also tweeted Friday that Comey "has no credibility" and linked to a video from a website dubbed "Lyin' Comey," which was created by the Republican National Committee ahead of the book's publication in order to push their side of the story.

Trump's suggestion that Comey should be prosecuted appears to stem from the former FBI chief's arranging to leak a memo about a conversation he had with the president last year. Comey has previously said he began writing memos about his conversations with the president because he believed Trump would not be truthful about their interactions.

Comey told Congress under oath in June 2017 that he woke up in the middle of the night and decided to orchestrate a leak of the content of one of the memos, in hopes that a special counsel would be appointed to lead the Russia investigation.

"I asked a friend of mine to share the content of a memo with the reporter. I didn’t do it myself for a variety of reasons, but I asked him to because I thought that might prompt the appointment of a special counsel," Comey said.

The friend was Columbia Law professor Dan Richman, who told NBC News last year that Trump is wrong to claim that what Comey did was illegal. Richman said that to his knowledge, nothing in the one memo that he described to reporters was or has been deemed classified. While other memos have been deemed classified, there is no evidence to suggest that Comey leaked classified information.

Since Comey's firing last year, he and Trump have occasionally exchanged barbs on social media.

Trump suggested Comey should face prosecution in January, while Comey responded to Trump's accusation in March that as FBI director he had swept "tremendous leaking, lying and corruption at the highest levels of the FBI, Justice & State" under the rug.

"Mr. President, the American people will hear my story very soon. And they can judge for themselves who is honorable and who is not," Comey said in a March tweet.

Earlier this week, Comey tweeted a picture from a room in his home where he was interviewed by ABC's George Stephanopoulos for an exclusive interview about his interactions with Trump, among other topics in his book, that is scheduled to air on Sunday.

“Not how my house normally looks,” Comey tweeted. “One chair for George, one for me.”