Emails from Hillary Clinton’s home server contained information classified at levels higher than previously known, including a level meant to protect some of the most sensitive U.S. intelligence, according to a document obtained by NBC News.

In a letter to lawmakers, the intelligence community’s internal watchdog says some of Clinton’s emails contained information classified Top Secret/Special Access Program, a secrecy designation that includes some of the most closely held U.S. intelligence matters.

Two American intelligence officials tell NBC News these are not the same two emails from Clinton’s server that have long been reported as containing information deemed Top Secret.

The letter doesn’t make clear whether Clinton sent or received the emails in question, but in the past, emails containing classified information have tended to have been sent to Clinton, not written by her.

The new revelation underscores the extent to which the email classification issue could continue to dog Clinton, as State Department and intelligence officials review sensitive information within messages that were blacked out before being released to the public.

Clinton, who tops national primary polling as a Democratic presidential candidate, has repeatedly said that none of the information she sent or received while secretary of state was marked classified  www.nbcnews.com/news/us-news/hillary-clinton-emails-contained-info-above-top-secret-ig-n499886

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