Former FBI director James Comey has told US lawmakers he was never instructed to shut down the FBI's Russia investigation - although he accepts he was fired because of that same inquiry.
Comey, who was fired last month, is currently testifying before the Senate select committee on intelligence, as part of its inquiry into Russian involvement in Donald Trump's election victory.
Comey was himself investigating Trump's relationship with Russia prior to his dismissal, and his appearance before Congress has been hugely anticipated, with some commentators likening it to the Watergate scandal in terms of magnitude.
The former Bureau boss told the Senate committee that, although he himself doesn't know why he was fired, he is willing to take Trump at his word and accept that the Russia inquiry was the overriding factor.
Nonetheless, when asked whether Trump at any time asked him to stop the FBI's Russia probe, Comey replied "not to my knowledge, no."
The witnessed reiterated his conviction that, despite denials from the Trump camp, he is convinced Russia hacked the US election, and indeed said Russian hackers had been waging a huge cyber-offensive against high-value targets dating back to 2015.
Addressing a question from New Mexico senator Martin Heinrich about the alleged interference, Comey said: "There should be no fuzz on this whatsoever. The Russians interfered in our election in the 2016 election cycle ...
"It is a high-confidence judgment of the entire intelligence community, and the members of this committee have seen that intelligence ... It’s not a close call."
Comey also said that, when he was fired, Trump and the White House "chose to defame me" and their attempts were based on "lies, plain and simple." Before he was fired, Comey said, Trump had repeatedly praised his performance and said he was doing a great job.
When asked why he chose to record a meeting with Trump prior to his assumption of the presidency in late January, Comey said he was concerned the Republican billionaire would release untrue information - a statement which is likely to heap further scrutiny and ridicule on Trump and his team.
Turning to the wider significance of the Russia allegations, Comey said it was a non-paertisan issue, adding "they're coming after America, which I hope we all love equally, and want to undermine our credibility in face of the world."
Trump had earlier attempted to goad his former FBI director by writing on Twitter "James Comey better hope that there are no 'tapes' of our conversations before he starts leaking to the press!”
However Comey appeared unconcerned about Trump's comment in his testimony, saying "Lordy, I hope there are tapes."