WASHINGTON - Government investigators have discovered four emails containing what they say is classified information on the personal email account that Hillary Rodham Clinton used as secretary of state, the investigators said in a letter to Congress released Friday.
Clinton meanwhile said Friday that she would stay focused on the issues at the heart of her presidential campaign, and that she was concerned about "a lot of inaccuracies'' in the reporting of her personal email account.
"Maybe the heat is getting to everybody,'' she said at a campaign event at New York University.
"We are all accountable to the American people to get the facts right, and I will do my part," Clinton added. "But I'm also going to stay focused on the issues, particularly the big issues, that really matter to American families."
The government investigators discovered the four emails while reviewing a sampling of 40 emails from Clinton's account. Of those, four contained information that should have been marked classified and should have been sent and stored on a secure computer system, I. Charles McCullough III, the inspector general of the intelligence community, the internal watchdog for the nation's intelligence agencies, said in the letter to Congress.
The emails were routed through a private email server that Clinton set up in her home. Critics and security experts have questioned whether the practice made government secrets more vulnerable to security risks and hacking.
A spokesman for Clinton's campaign released a brief statement on Twitter, saying, "Any released emails deemed classified by the administration have been done so after the fact, and not at the time they were transmitted."
The discovery of the four emails has prompted the inspector general to refer the matter to FBI counterintelligence agents, who investigate crimes related to mishandling classified information. On Thursday night and again Friday morning, the Justice Department referred to the matter as a "criminal referral" but later on Friday dropped the word "criminal."
Regardless of the terminology, the referral raises the possibility of a Justice Department criminal investigation into Clinton's emails as she campaigns for president. Polls show she is the front-runner for the Democratic nomination by a wide margin.
Justice Department officials said no decision had been made about whether to investigate.
Since Clinton's use of a private email account for official State Department business was revealed in March, she has repeatedly said she had no classified information on the account.
State Department officials, however, told the inspector general that the account potentially contained hundreds of classified emails. When McCullough's investigators performed the spot check of 40 emails, he said, 10 percent contained classified information, he said.
A second inspector general, this one for the State Department, is also investigating the department's handling of Clinton's emails. The two inspectors general have sent Congress a series of memos, including one dated June 29 that said Clinton's private account contained "hundreds of potentially classified emails." The memo was written to Patrick F. Kennedy, the undersecretary of state for management.
At issue are thousands of pages of State Department emails from Clinton's private account. Clinton has said she used the account because it was more convenient, but it also shielded her correspondence from congressional and Freedom of Information Act requests.
She faced sharp criticism after her use of the account became public, and subsequently said she would ask the State Department to release her emails.
The department is now reviewing some 55,000 pages of emails. A first batch of 3,000 pages was made public June 30.
In the course of the email review, State Department officials determined that some information in the messages should be retroactively classified. In the 3,000 pages that were released, for example, portions of two dozen emails were redacted because they were upgraded to "classified status." But none of those were marked as classified at the time Clinton handled them.
In a second memo to Kennedy, sent July 17, the inspectors general said that at least one email made public by the State Department contained classified information. The inspectors general did not identify the email or reveal its substance.