Two years before the public learned of Hillary Clinton’s private server, the State Department gave an “inaccurate and incomplete” response about her email use when it told an outside group that it had no documents about Clinton’s email accounts beyond her government address, according to a report from the State Department’s inspector general to be released Thursday.

The State Department made its statement in response to a 2012 records request from the independent watchdog group Citizens for Responsibility and Ethics in Washington (CREW). The response came even though Clinton’s chief of staff, who knew about the secretary’s private account, was aware of the inquiry, the report says. In addition, the IG review found that agency staffers had not searched Clinton’s office for emails.

The incident was one of four cases that the report highlights as examples of flawed responses to public-records requests made while Clinton was in office. The report found it was part of a long-standing problem stretching back through previous administrations.

Clinton’s exclusive use of a private email system, which became public in March 2015, led to an FBI investigation into whether her unusual arrangement had compromised national secrets.

After a firestorm of controversy, Clinton’s email practice has become more muted as a campaign issue in recent months as she has maintained her status as the Democratic presidential front-runner.

Catch up on the controversy and read the emails

But the new report demonstrates the potential peril Clinton still faces over the issue. In addition to the FBI probe, the State Department inspector general, Steve Linick, indicated that his work is not done.

His office is preparing an additional report that could touch even more directly on Clinton’s conduct — examining the use of personal email and its effect on the department’s compliance with its duty to preserve records.

Pointing to the report’s broad conclusions about weak records management, State Department officials concurred with the inspector general’s findings and recommendations to boost staff, training, procedures and oversight.

“The Department is committed to transparency, and the issues addressed in this report have the full attention of Secretary Kerry and the Department’s senior staff,” said spokesman John Kirby, referring to Clinton’s successor, John F. Kerry. “We know we must continue to improve our FOIA responsiveness and are taking additional steps to do so.”

Brian Fallon, a spokesman for the Clinton campaign, said, “The Department had a preexisting process in place to handle the tens of thousands of requests it received annually, and that established process was followed by the Secretary and her staff throughout her tenure.”

The report said that some seeking records from the secretary’s office have had to wait more than 500 days to get replies. The secretary’s office lacked any written procedures for handling records requests and had no senior official in charge of overseeing the work, the report says.

Of 417 records requests made from the era of Madeleine K. Albright to the present, 243 are still open and pending.

Democratic presidential candidate Hillary Clinton responded to reporters in Las Vegas on Tuesday over the controversy surrounding her personal e-mail server. Clinton reiterated that she did not send or receive any classified material from her personal account. (AP)

The inquiry found that the secretary’s office almost never searched its own email in ­public-records requests before 2011. From 2011 to 2015, the secretary’s office inconsistently searched office emails as it saw fit.

The 2012 request by CREW was sparked by the discovery that Lisa Jackson, then-administrator of the Environmental Protection Agency, had been using an alias email at work with the name “Richard Windsor,” largely for personal communication.

CREW filed a public-records request with the State Department that month for “records sufficient to show the number of email accounts of or associated with Secretary Hillary Rodham Clinton.”

Staff soon after alerted Clinton’s chief of staff, Cheryl Mills, to CREW’s request. The inspector general found that Mills tasked a member of her staff to follow up on the request. In May 2013 — four months after Clinton left office — the State Department told CREW that “no records responsive to your request were located.”

The IG report cited no evidence that Mills intervened in the CREW inquiry or approved the final response — only that she knew about the request and wanted a close aide to keep track of it.

A lawyer for Mills did not respond to a request for comment.

Melanie Sloan, the executive director of CREW at the time, said Wednesday that the findings showed the agency should have known its response was wrong.

“Cheryl Mills should have corrected the record,” Sloan said. “She knew this wasn’t a complete and full answer.”

Fallon, noting that the report found no sign that Mills reviewed the CREW records response, said Mills “did absolutely nothing wrong.”

Correction: An earlier version of this story and its headline incorrectly stated that Hillary Clinton was secretary of state when the agency issued an inaccurate response to a request about email use. The request came while she was in office, but the agency’s response was issued after she had departed.