FBI director James Comey has revealed former presidential hopeful Hillary Clinton's suggestions he "swayed" the US presidential election make him "mildly nauseous".
Mr Comey has spoken to Senators for the first time about why he revealed the FBI had reopened the investigation into Hillary Clinton's emails a fortnight before the election in November 2016 - and he defended his decision, saying failing to inform Congress would have been worse.
"To not speak about it would require an act of concealment in my view. Concealing, in my view, would be catastrophic," he said.
"It makes me mildly nauseous to think that we might have had some impact on the election, but honestly, it wouldn't change the decision."
Mr Comey says it was one of the world's "most painful experiences" but said he'd still make the same call if he was in the same position again.
Ms Clinton lost her lead in the polls in the final two weeks of the election, and on Tuesday said the announcement cost her the election.
"I was on the way to winning until a combination of Jim Comey's letter on October 28 and Russian WikiLeaks raised doubts in the minds of people who were inclined to vote for me but got scared off," she said.
"If the election had been on October 27, I would be your President."
However Mr Trump has responded to Ms Clinton's comments on Twitter overnight, saying she's fortunate that Mr Comey covered her alleged misdemeanours.
"FBI Director Comey was the best thing that ever happened to Hillary Clinton in that he gave her a free pass for many bad deeds!" he wrote.
"The phony Trump/Russia story was an excuse used by the Democrats as justification for losing the election. Perhaps Trump just ran a great campaign?"
White House advisor Kellyanne Conway also mocked Ms Clinton for blaming the FBI and misogyny for her loss, and gave her own list of reasons for her unsuccessful presidential bid.
The comments take aim at both Ms Clinton and the FBI, which said in December 2016 it was likely Russia was responsible for hacking the Democratic emails in an attempt to sway the election in his favour.