US Democratic presidential nominee Hillary Clinton called on the Federal Bureau of Investigation to explain its reopened investigation into her emails and release all available information immediately.

WASHINGTON (Sputnik) — Earlier in the day, Comey informed the US Congress that the FBI discovered new emails sent from Clinton's private server during the course of an unrelated investigation. Comey said investigators would review the new emails to determine if they contain classified information.

"I’m confident whatever they are will not change the conclusion reached in July," Clinton said at an impromptu news conference Friday on the FBI’s action. "It’s imperative that the bureau explain this issue in question, whatever it is, without any delay."

Clinton has been criticized for the use of a private email server and account for official business during her 2009-2013 tenure as secretary of state. In July, Comey described Clinton's conduct as extremely careless but said it did not warrant criminal charges.After the initial FBI probe, Comey in September described Clinton's use of a nongovernment email system for official business while the top US diplomat as "extremely careless," but he recommended against filing criminal charges against her.

In 2014, Clinton released more than 55,000 emails from the private server to State Department investigators, claiming the documents contained only work-related information. She has admitted to erasing 33,000 emails.