Twenty-two emails from Hillary Clinton's private email server have been marked "top secret" and won't be released, the State Department said Friday.
The emails were not marked as classified at the time they were sent.
"We can confirm that later today, as part of our monthly FOIA productions of former Secretary Clinton's emails, the State Department will be denying in full seven email chains, found in 22 documents representing 37 pages," State Department spokesman John Kirby told reporters.
The documents are being upgraded at the request of the intelligence community because they contain a category of top secret information," Kirby said.
Clinton campaign spokesman Brian Fallon said that Clinton said the emails should be released and called at least one case "overclassification run amok."
Clinton campaign: This is overclassificationJan. 29, 201610:59
"We firmly oppose the complete blocking of the release of these emails," Fallon said in a statement. "Since first providing her emails to the State Department more than one year ago, Hillary Clinton has urged that they be made available to the public. We feel no differently today."
The revelations come just days before the Iowa caucuses where Clinton is in a tight battle with fellow Democratic presidential candidate Sen. Bernie Sanders. Clinton has been dogged by the issue throughout the campaign season as several investigations, including one by the FBI, are examining whether government information was compromised.
Kirby also announced today that 18 emails — from 8 distinct chains — between then Secretary Clinton and President Barack Obama are being withheld from the court-ordered FOIA release, because of the law governing the release of presidential documents.
Their classification level has not yet been determined.
This article originally appeared on NBCNews.com.