Democratic candidate Hillary Clinton says she is “confident” a new FBI probe linked to her emails will not change its original finding that she should not be prosecuted.
She called on the FBI director to explain the new inquiry to the American people.
James Comey earlier said the FBI was looking into newly found messages.
The latest emails came to light during a separate inquiry into top Clinton aide Huma Abedin’s estranged husband, former congressman Anthony Weiner.
Devices belonging to Huma Abedin and Anthony Weiner were seized in an investigation into whether he sent explicit emails to a 15-year-old girl in North Carolina.
Hillary Clinton said: “The American people deserve to get the full and complete facts immediately.
She highlighted that James Comey had said he did not know the significance of the new emails, adding: “I’m confident (that) whatever they are will not change the conclusion reached in July.”
Donald Trump, however, described the FBI investigation as “the biggest political scandal since Watergate”, referring to the 1970s scandal that engulfed Republican President Richard Nixon.
“It’s everybody’s hope that justice at last can be delivered,” the Republican candidate told supporters at a rally in Iowa.
“The FBI would never have reopened this case at this time unless it were a most egregious criminal offence.”
James Comey said the FBI would investigate if the newly discovered emails contain classified information.
The FBI chief said in a letter to Congress that investigators had discovered the emails “in connection with an unrelated case… that appear to be pertinent to the investigation”.
James Comey said he “cannot yet assess whether or not this material may be significant, and I cannot predict how long it will take us to complete this additional work”.
The FBI has already established Hillary Clinton had classified information on a private email server.
In July, James Comey said Hillary Clinton’s handling of sensitive material during her 2009-2013 tenure as secretary of state was “extremely careless”, but cleared her of any criminal wrongdoing.
The revelation that Hillary Clinton handled sensitive information while breaking federal rules by running her own email server out of her upstate New York home has dogged her campaign since last year.
Her campaign chairman John Podesta criticised the FBI’s “extraordinary” timing.
The revelation comes just 11 days before Americans go to the polls in the presidential election.
Hillary Clinton is five points ahead of Donald Trump, according to a Real Clear Politics average.