US election: FBI's Clinton emails move defended by Comey
FBI director James Comey has defended his decision to brief US lawmakers on FBI moves to look again into Hillary Clinton's email use, US media say.
Not making it public would be "misleading", he said. He was aware of a risk of being "misunderstood", given that the FBI does not know the significance of the newly found emails.
Mrs Clinton said the FBI's move was "unprecedented" and "deeply troubling".
Her Republican rival Donald Trump has praised the bureau's decision.
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On Friday, just 11 days before the presidential election, Mr Comey wrote to Congress, saying the FBI had learned of fresh emails which may be "pertinent" to its previous inquiry into the Democratic presidential candidate's use of a private server when she was secretary of state.
He has been heavily criticised by Clinton supporters - and according to the New York Times, justice department officials - for his decision to make the information public so close to polling day.
But he said he felt an "obligation" to do so given that he had previously testified that the FBI investigation was complete.
Addressing cheering supporters at a rally in the key election state of Florida on Saturday, Mrs Clinton said: "It's pretty strange to put something like that out with such little information right before an election."
Earlier, Clinton campaign chairman John Podesta said the information provided by Mr Comey was "long on innuendo" and "short on facts", with "no evidence of wrongdoing. No charge of wrongdoing. No indication this is even about Hillary".
Mr Podesta said that 24 hours from Mr Comey's revelation, there was no real explanation for why he had decided to send that letter. The more that information had emerged, he said, "the more it seems overblown".
The FBI has already established that Mrs Clinton had held classified information on a private email server.
In July, Mr Comey said Mrs Clinton's handling of sensitive material during her tenure as secretary of state was "extremely careless", but cleared her of any criminal wrongdoing.
The latest emails were discovered as part of a separate investigation into the estranged husband of top Clinton aide, Huma Abedin.
Devices belonging to her and Anthony Weiner, a former high-flying congressman, were seized in an investigation into whether he sent sexually explicit emails to a 15-year-old girl in North Carolina.
Mrs Clinton said she was "confident" the investigation into the emails would not change the FBI's original finding in July.
"It's imperative that the bureau explain this issue in question, whatever it is, without any delay," she told reporters on the campaign trail in Des Moines, Iowa, on Friday.
Mr Trump said the move was the "biggest political scandal since Watergate", referring to the 1970s scandal that engulfed then-Republican President Richard Nixon.
He said he has "great respect" for the FBI and the justice department, now that they were "willing to have the courage to right the horrible mistake that they made" in ending the investigation earlier.
'October surprise' for Clinton - US media react
- "The question will be how badly damaged was Ms Clinton's candidacy by the 11th-hour re-eruption of a controversy that never should have generated so much suspicion or accusation in the first place" - Washington Post
- "Mrs Clinton's apparent effort to blunt scrutiny by means of that private server has only led to far more damaging scrutiny and suspicion, with no end in sight" - New York Times
- "Dashed are the hopes that the campaign could come to a conclusion on a high note, instilling in Americans a feeling that casting a history-making vote for Clinton is something more than merely a repudiation of Donald Trump" - Politico's Annie Karnie
- "If past is prologue, and it usually is, then a Hillary Clinton presidency may be engulfed and disabled by scandal... In other words, her presidency could be dead on arrival" - Fox News' Gregg Jarrett
The former secretary of state's private email server was first revealed in March 2015 by the New York Times.
She did not immediately express regret, and said the main reason for her "firstname.lastname@example.org" address was "convenience".
Soon after that she apologised in an interview with ABC News, and has since said sorry to voters a number of times.
Opinion polls suggest Mrs Clinton is four points ahead of Mr Trump, according to a Real Clear Politics average.