The US Justice Department says it has received a request to probe whether Hillary Clinton mishandled sensitive government information by using her private email for State Department business.
"The Department has received a referral related to the potential compromise of classified information," a department official said in a brief statement on Friday that confirmed in part a story that first appeared in The New York Times.
Contrary to what the Times reported, the department official said the request was not for a "criminal" investigation.
The Times reported that the request follows a recent assessment by inspectors general for the State Department and US intelligence agencies that Clinton's private account contained "hundreds of potentially classified emails."
The assessment sent was written to Patrick Kennedy, US undersecretary of state for management, it said.
Inspectors general are internal investigators within a government agency.
Clinton - an ex-US senator and former first lady, in addition to being a onetime secretary of state - is running for the US presidency.
She has accused her political enemies of fabricating a controversy over the emails in an effort to dim her White House prospects.
She is widely viewed as the Democratic Party's probable candidate in next year's presidential election.
Clinton used her private email account for State Department correspondence to communicate with staffers, dignitaries and others between 2009 and 2013, but says she had no classified information on the account.