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Hillary Clinton in damage control over latest email revelation

Hillary Clinton is in damage control over new information about the private email server she used as secretary of state, reports CBS News correspondent Julianna Goldman.

The State Department released a new batch of the emails, saying that 22 of them contain top secret information, but that they were not labeled "classified" when they were sent. Those messages were spread over seven email chains totaling 37 pages.

"In consultation with the intelligence community, we are making this upgrade and we believe it's the prudent, responsible thing to do.," State Department spokesman John Kirby said.

This is the first time the State Department has acknowledged that material found on Clinton's email server was top secret, one of the highest levels of classification - so secret that the emails weren't even partially included in Friday's release. Kirby would not share the topics of the emails, or say whether Clinton was the sender or receiver.

The timing was also sensitive, coming just two days before the Iowa caucuses. The controversy quickly made its way to the campaign trail.

Clinton didn't address the controversy during a campaign stop in Iowa Friday, but Republicans were quick to pounce.

Donald Trump tweeted:

"What I know for a fact is that if a member of my staff on the Intelligence Committee had done that, they'd have been fired and probably would have been prosecuted," Sen. Marco Rubio told reporters.

Clinton's chief Democratic rival, Sen. Bernie Sanders, didn't bite. He released a statement saying the legal process shouldn't be politicized.

Clinton's campaign has pushed back, saying the move is "over-classification run amok," the result of "bureaucratic infighting." They argue that in one case, the emails appear to involve information from a published news article.

Clinton kept a private email server at her New York home. She says she never sent or received classified information on her private email account.

But the controversy has led to question among voters about her honesty.

In an interview with NBC News, Clinton downplayed those questions:

"I just don't see it as anything that will in any way cause any voter to - a voter with an open mind - to have any concerns."

An intelligence official tells CBS News that some of the information in the emails is so sensitive that Clinton and her aides should have known never to discuss it over an unsecure system in the first place.