Hillary Rodham Clinton hands off her mobile phone before a Dec. 8, 2011 meeting in the Netherlands. The State Department is reviewing whether her e-mails included sensitive information and, if so, whether proper security protocols were in place. (J. Scott Applewhite/AP)

Clarification: This story has been updated to clarify the State Department’s explanation of the review’s initial purpose.

A State Department review of Hillary Rodham Clinton’s e-mails from her time leading the agency could reveal whether she violated security policies with her use of a private e-mail server, a senior department official said Thursday night.

The agency is reviewing tens of thousands of pages of Clinton’s e-mails to determine whether they can be released to the public.

The official, requesting anonymity to discuss sensitive internal deliberations, said that Clinton’s use of personal e-mail did not automatically break the rules, but the analysis could show whether work e-mails sent from her personal account included sensitive information that is typically required to be handled on a system that meets security protocols.

The official said the department would not know whether Clinton followed the rules until officials review the portion of ­e-mails that she turned over last year as part of an agency effort to retrieve public records.

In a tense exchange with reporters Wednesday, State Department deputy spokeswoman Marie Harf denied anything inappropriate occurred after revelations that former secretary of state Hillary Clinton used a private e-mail account for work. (C-SPAN)

The official’s comments are the first time the agency has indicated any uncertainty about whether Clinton complied with its e-mail policies.

“We are not going to prejudge the outcome of the review of Secretary Clinton’s 55,000 pages of e-mails,” the official said.

Clinton’s unusual e-mail practices have led to a storm of criticism this week from government-transparency advocates and ­Republican lawmakers, who say she has used the system to assert control over decisions regarding e-mails that would be released under federal public records law.

The controversy has created a new political complication for Clinton, the presumptive Democratic front-runner for president, with some Democrats expressing concern that her penchant for secrecy could become a weakness in the general election next year.

Clinton submitted the 55,000 pages of e-mails last year to the State Department after agency officials asked her to turn over public records in her possession.

State Department officials have said that Clinton and her private staff, not the agency, decided which of her e-mail correspondence from her four years in office to turn over.

The agency under Clinton’s tenure did enforce restrictions on the use of private ­e-mail.

A 2012 report by the State Department’s inspector general said an ambassador’s use of private e-mail for public work was a violation of agency rules and created security risks. It was one of a string of criticisms that led to the forced resignation of the ambassador, Scott Gration, who had been posted in Kenya.

The report said that agency policies permitted the use of private e-mails only for “maintaining communication during emergencies.”

Department policy requires that “normal day-to-day operations be conducted on an authorized information system, which has the proper level of security controls.”

An unauthorized system, the report said, increases the risk of “data loss, phishing, and spoofing of e-mail accounts.” In addition, the report warned that private ­e-mail use could result in the “loss of official public records” because many systems do not have “approved record preservation or backup functions.”

State Department officials have not answered questions about whether Clinton received a legal opinion from the agency before using her private e-mail system, which was created as she took office in 2009. They have not said how the system worked, who installed it, or what steps were taken to ensure security and proper backup.

Clinton took to Twitter late Wednesday to call on the State Department to promptly release the records, saying, “I want the public to see my e-mail.”

On Thursday, her successor, Secretary of State John F. Kerry, promised that officials would review and publicly release the ­e-mails that had been provided by Clinton.

Kerry told reporters during a visit to Saudi Arabia that agency officials would “undertake this task as rapidly as possible.” But a State Department spokeswoman acknowledged the process would be time-consuming, given the volume of the record.

The pledge did little to satisfy Clinton’s political opponents or advocates for open access to government.

Federal records laws generally require agencies to release ­e-mails, exempting only those that fall in certain categories of sensitive, classified or personal information.

Moreover, Clinton did not address how she would handle records she did not submit to the State Department.

A Clinton aide would not say Thursday how many e-mails were withheld or describe the process used to decide which were purely personal.

Of the e-mails that were turned over to State, the Clinton aide said, 90 percent were correspondence between Clinton and agency employees using their regular government e-mail accounts, which end in state.gov.

The remaining 10 percent were communications between Clinton and other government officials, including some at the White House, along with an unknown number of people “not on a government server,” the aide said. The aide requested anonymity because the e-mails are not yet public.

Alice Crites contributed to this report.