Ex-FBI chief James Comey yesterday told Congress that the Trump administration's comments about him and the FBI were "lies plain and simple", reports BBC. Comey told a Senate committee they were wrong to denigrate the agency and its leadership. He was also "confused" by the "shifting explanations" for his sacking, which came as he led a probe into any links between the Trump campaign and Moscow.
President Donald Trump later said he never sought to impede the inquiry.
In his testimony, Comey said Mr Trump had repeatedly told him he was doing a "great" job.
He also suggested he was fired to "change the way the Russia investigation was being conducted".
"I know I was fired because something about the way I was conducting the Russia investigation was some way putting pressure on him, was some way irritating him," Comey said of the president.
The former FBI boss remained largely composed throughout almost three hours of testimony but became impassioned when delivering his opening remarks.
He told the panel that the White House "chose to defame me, and more importantly the FBI" by claiming the agency was "poorly led".
"Those were lies, plain and simple. And I'm so sorry that the FBI workforce had to hear them," he continued.
"The FBI is honest. The FBI is strong. And the FBI is and always will be independent," he said in his opening remarks.
Comey was leading one of several Russia investigations
before Trump fired him. US intelligence agencies believe Russia interfered in the US election and they are investigating alleged links between the Trump campaign and Moscow.
But there is no known evidence of collusion and President Donald Trump has dismissed the story as "fake news".
His spokeswoman Sarah Sanders on Thursday hit back at Comey, saying: "I can definitively say the president is not a liar."
For Donald Trump the good news from James Comey's testimony is that the former FBI director clearly said the president was not directly under FBI investigation at the time he was fired. The bad news was, well, everything else.
On multiple occasions, Comey said he was either concerned or knew that the president or his administration was lying "plain and simple" - about the circumstances of his dismissal and about the nature of his meetings with the president.
It's clear the president woefully mishandled this, for which he has paid a high price ever since. By unceremoniously sacking him, and offering a muddle of explanations for it, he created an adversary with both the means and the motivation to respond in the most damaging way.
Comey had a friend leak disturbing information about the president's actions to the media. He was given the biggest spotlight in a generation to publicly air further details. He stood before a Senate committee not just to defend himself, but also the honour of the FBI.
The White House may claim today's testimony is a technical exoneration. Politically, however, it's a staggering blow. And when it comes to the presidency, politics is everything.