The FBI says it's found new emails related to Hillary Clinton's controversial use of a personal email server to handle US government business and that the bureau is reviewing the messages to "assess their importance to our investigation."
In a letter sent to Congress on Friday, FBI Director James Comey mentioned that he'd previously testified that the bureau's inquiry into the server issue had been completed but that now he was writing "to supplement my previous testimony."
The new emails surfaced in connection with an unrelated case, Comey said, and the bureau is determining whether they contain classified information.
That unrelated case is reportedly the investigation into the August sexting scandal of Anthony Weiner, the husband of top Clinton aide Huma Abedin. The FBI seized electronic devices shared by Weiner and his estranged wife.
"The FBI cannot yet assess whether or not this material may be significant," Comey wrote in the letter to members of several committees, "and I cannot predict how long it will take us to complete this additional work."
Clinton's use of the server while she was secretary of state has been a hot issue during the US presidential campaign. It's raised questions about the handling of classified information by now-Democratic nominee Clinton and her aides and given her Republican rival, Donald Trump, ammunition for attacks on her trustworthiness.
In July, Comey said a yearlong investigation did not "support bringing criminal charges" against Clinton but that she and her associates had been "extremely careless in their handling of very sensitive, highly classified information."
The Clinton campaign did not immediately respond to a request for comment.