A US judge has ordered the State Department to review and determine the potential release of 14,900 documents, most of which are believed to be emails to or from Hillary Clinton, that turned up in an FBI investigation of her use of a private email server as secretary of state.
The documents are part of a cache that the FBI turned over to the State Department at the end of its probe into Ms Clinton's use of the server.
The Federal Bureau of Investigation found Ms Clinton was "extremely careless" with sensitive information by using the private server but recommended against bringing charges against her. She has been dogged by questions about the issue throughout her run for the White House.
The State Department could make public the first batch of emails in October, weeks before the Democratic nominee faces Republican rival Donald Trump in the November 8 election. State Department employees are due to craft a timeline for the release at a meeting on September 23.
The revelation of more emails after 55,000 pages of emails were turned over by Ms Clinton last year could provide continued fodder for opponents who have seized on the email issue to charge she is untrustworthy.
The announcement by US District Court Judge James Boasberg, who is overseeing a group of lawsuits seeking to make Ms Clinton's emails public, came the same day a conservative watchdog group, Judicial Watch, made public a batch of Ms Clinton's emails obtained through a lawsuit.
Judicial Watch says that the emails show donors to Clinton family's charitable foundation seeking the access to her during the period she was secretary of state from 2009-2013.
The 14,900 documents referred to by Boasberg are believed to include emails that were not included among the 55,000 pages of emails that Ms Clinton previously turned over to the State Department after her use of a private email server and private email account became public last year.
The new documents are believed to consist chiefly of emails to or from Ms Clinton, said a US official who spoke on condition of anonymity, and may include a mix of personal and work emails. Some of the emails were found on the servers of people she or her staff were communicating with.
Ms Clinton, who is currently leading Mr Trump in opinion polls ahead of the election, has said she did not compromise classified information and used a private server for convenience, and later apologized, saying "I take responsibility."
Meanwhile, former Secretary of State Colin Powell over the weekend dismissed reports that Ms Clinton told federal investigators that it was at his suggestion that she used a personal email account, according to a media report.
Powell, who served as the nation's top diplomat from 2001-2005 under Republican president George W. Bush, told People magazine that while he did send Ms Clinton a memo about his own email practices, Ms Clinton had already chosen to use her personal email rather than a government account while she had the job.