U.S. federal investigators have said they will look into new e-mails that have surfaced related to Democratic presidential nominee Hillary Clinton's use of a private server.
The announcement, made by FBI Director James Comey in a letter to Congress, injected major new uncertainty into the U.S. presidential campaign, with less than two weeks before Election Day.
The FBI had already investigated whether Clinton's use of a private e-mail server while she was secretary of state might have resulted in the mishandling of classified information.
Comey announced in July that investigators found nothing illegal, but chided Clinton for bad judgement.
Clinton apologized for the decision.
The news that the FBI was investigating additional emails could potentially roil the race between Clinton and her Republican opponent, Donald Trump.
Trump has repeatedly criticized Clinton for the e-mail issue, and has even called for a special prosecutor.
Most major opinion polls show Clinton with a substantial lead over Trump.
