At the request of the FBI, the U.S. State Department has suspended plans for an internal review of whether classified information was properly handled in former Secretary of State Hillary Clinton's emails, a spokeswoman said on Friday.

Clinton, the front-runner in the race for the Democratic Party nomination in the Nov. 8 presidential election, has apologized for using a private email server for official business while in office from 2009 to 2013 but said she did nothing wrong. The Federal Bureau of Investigation is probing the arrangement.

On Jan. 29, the State Department said 22 emails sent or received by Clinton had been upgraded to top secret at the request of intelligence agencies and would not be made public as part of the release of thousands of Clinton's emails. It said none of the emails was marked classified when sent.