Federal investigators have alerted the Justice Department to a "potential compromise of classified information" arising from the private email server used by former Secretary of State Hillary Rodham Clinton in her home, a department official said Friday.

A memo signed this week by the inspector general of the intelligence community to members of Congress said the IG's office had identified "potentially hundreds of classified emails" among the 30,000 that Clinton had provided and that are now being processed for public release.

None of the emails were marked as classified at the time they were sent or received, but some should have been handled as such and sent on a secure computer network, according to the letter to congressional oversight committees from I. Charles McCullough III.

Clinton, campaigning in New York, commented briefly on the issue. She said, "We are all accountable to the American people to get the facts right, and I will do my part but I'm also going to stay focused on the issues."

The inspector general's office said it raised concerns to FBI counterintelligence officials that "these emails exist on at least one private server and thumb drive with classified information and those are not in the government's possession," said Andrea Wilson, a spokeswoman for the office of the Inspector General of the Intelligence Community.

A U.S. official said it was unclear whether classified information was mishandled and that the intelligence community letter to the Justice Department alerting it to the potential problem didn't suggest any wrongdoing by Clinton, the leading Democratic candidate in the 2016 presidential race.

The officials weren't authorized to discuss the referral publicly and spoke only on condition of anonymity.

The memo from McCullough to Congress, dated Thursday, also said that his office had identified the accidental release of national security information during the process of reviewing Clinton's emails and preparing them for release. The inspector general said he had recommended that the review of the emails be done on a top secret computer network and that the State Department should better coordinate with the Justice Department during the review process.

Clinton's campaign said that she had "followed appropriate practices in dealing with classified materials."

"Any released emails deemed classified by the administration have been done so after the fact, and not at the time they were transmitted," campaign spokesman Nick Merrill said in a statement.

It was not immediately clear whether the Justice Department would investigate the matter, but the existence of the referral suggests that Clinton is likely to face lingering questions during the presidential campaign over her personal email account - an issue that has dogged her for months and that Republicans have used to criticize her.

"The number of questions surrounding Secretary Clinton's unusual email arrangement continues to grow," said Rep. Trey Gowdy, a South Carolina Republican who is chairing a special committee investigating the 2012 deadly attacks in Benghazi, Libya.

Reince Priebus, chairman of the Republican National Committee, reiterated his call for Clinton to turn over her personal email server to an independent third party.

Facing questions in March, Clinton said that as secretary of state she had used a personal email account as a matter of convenience to limit the number of electronic devices she used. She maintained then that she had never sent classified information. Earlier this month, the State Department made public some 3,000 emails involving Clinton covering March through December 2009, and is under court order to make regular further releases of such correspondence.

The aim is for the department to unveil 55,000 pages of her emails by Jan. 29, 2016. But a federal judge this month chastised the State Department for moving too slowly in providing The Associated Press with thousands of emails submitted through the Freedom of Information Act.

The Justice Department receives many referrals that it decides not to take up, and decisions about what to pursue often take some time.