Last Updated Jul 24, 2015 12:41 PM EDT
This story and headline have been updated to reflect a correction issued by the Justice Department saying, "The Department has received a referral related to the potential compromise of classified information. It is not a criminal referral."
The Justice Department has been asked by at least one inspector general for an investigation into the use by Democratic presidential front-runner hopeful Hillary Clinton of a private email account for official business while she was secretary of state - which has already come up as an issue in the 2016 campaign - a Justice Department official confirmed to CBS News.
The story was first reported by The New York Times, citing senior government officials.
The move comes after a conclusion in a June 29 memo by the inspector general for the State Department and the inspector general for the Intelligence Community [IC] that Clinton's private account had "hundreds of potentially classified emails" in it. The memo was sent to Patrick F. Kennedy, the under secretary of state for management.
In a July 17 letter to Kennedy, the inspectors general wrote that the IC inspector general has received confirmation from IC Freedom of Information Act [FOIA] officials that "several of these emails contained classified IC information, though they were not marked as classified."
Additionally, CBS News has obtained a letter sent Thursday to the leadership of the House and Senate intelligence committees, in which the IC inspector general says some of the emails on Clinton's server "should have been handled as classified, appropriately marked, and transmitted via a secure network." He also reveals that the emails in question were "purported to have been copied to a thumb drive in the possession of former Secretary Clinton's personal counsel, Williams and Connelly attorney David Kendall."
What's not clear is whether any information in the emails was marked as classified by the State Department when Mrs. Clinton sent or received them -- some information could have been retroactively classified. As the Times reported, about two dozen emails were redacted before they were publicly released because they were upgraded to "classified status."
In the Times' initial report, the investigation was described as pertaining to whether Clinton specifically "mishandled sensitive government information." That characterization was changed in a subsequent version of the story.
Since Clinton's use of the private account was revealed in March, she has said repeatedly that the account contained no classified information. She has said using it was a matter of convenience.
The Justice Department hasn't decided if it will open a probe, the Justice officials told CBS News.
A spokesman for Mrs. Clinton's campaign released this statement Friday morning:
"Contrary to the initial story, which has already been significantly revised, she followed appropriate practices in dealing with classified materials. As has been reported on multiple occasions, any released emails deemed classified by the administration have been done so after the fact, and not at the time they were transmitted."
CBS News' Paula Reid contributed to this report