In a letter to members of Congress, the agency’s director James Comey revealed new messages have been found that are “pertinent to the investigation”.
In July, FBI officials had recommended that no charges should be brought over the controversy which centres around Ms Clinton’s use of a private email server to exchange messages with staff and other officials.
Her use of a private email server led many to think she was hiding secret information and putting the nation’s security at risk however she did not face a trial over the allegations.
It is understood that FBI investigators came across a device during a separate probe which led them to further messages. Read more