(CNN)Former FBI Director James Comey on Sunday called the House Intelligence Committee Republicans' year-long Russia investigation "a wreck" that damaged relationships with the intelligence community and the federal court that grants warrants to surveil foreigners.
The committee also released a redacted Democratic dissent document that said collusion exists and that Republicans failed to investigate key aspects of the matter.
Asked on NBC's "Meet the Press" whether the committee served "a good investigative purpose," Comey responded: "Not that I can see," adding that the probe became politicized "and it wrecked the committee, and it damaged relationships with the FISA Court, the intelligence communities. It's just a wreck."
Comey said the resulting GOP report "strikes me as a political document."
Trump tweeted about the report on Friday evening, saying it backs his claims that there is no truth to the allegations that his campaign colluded with Russia in Moscow's attempt to interfere in the election.
"House Intelligence Committee rules that there was NO COLLUSION between the Trump Campaign and Russia," Trump wrote. "As I have been saying all along, it is all a big Hoax by the Democrats based on payments and lies. There should never have been a Special Councel (sic) appointed. Witch Hunt!" Trump wrote on Twitter.
Comey disputed the President's assertions when asked during the interview Sunday whether they matched his views.
"That is not my understanding of what the facts were before I left the FBI, and I think the most important piece of work is the one the special counsel's doing now," Comey said.
Asked on Sunday whether he would consider Trump a credible witness if the President were to sit down for an interview with special counsel Robert Mueller, Comey said: "I have serious doubts about his credibility."
"Whether he were under oath or not?" host Chuck Todd asked?
"Correct," Comey said. "And sometimes people who have serious credibility problems can tell the truth when they realize the consequences of not telling the truth in an interview or in the grand jury would be dire. But you would have to go in with a healthy sense that he might lie to you."