An email stored on Hillary Clinton’s private email server contained information that was highly classified at the time it was sent, the Federal Bureau of Investigation revealed on Monday.

According to FBI interview notes in its Clinton investigation released on Monday, "one of these e-mails was TOP SECRET/SCI at the time of transmission."

The finding contradicts months of claims by Clinton, her campaign, and her political allies that she did not send or receive information that was classified at the time.

The TS/SCI designation is reserved for extremely sensitive national security information that can only be handled in secure settings such as Sensitive Compartmented Information Facilities (SCIFs).

Sensitive compartmented information is sometimes referred to as "above top secret" due to its highly sensitive nature, although it is not a separate classification category.

On the day after Clinton began her tenure as secretary of state, she signed two nondisclosure agreements that laid out criminal penalties for the mishandling of SCI and all other classified information.

The FBI this year declined to bring charges against Clinton despite those agreements.

After the Washington Free Beacon first reported on those nondisclosure agreements, "a source familiar with the situation" told Politico that none of Clinton’s emails contained TS/SCI information.

That claim was contradicted by the intelligence community’s inspector general at the time. The FBI’s findings further demonstrate that Clinton’s private email server, which she set up in violation of State Department rules and the guidance of top information security officials, contained TS/SCI information.

The FBI also revealed in notes released Monday that Clinton brought her Blackberry inside the State Department SCIF despite explicit warnings from department personnel that doing so could expose sensitive national security information to malicious cyber attacks.

Clinton "refused to abide by this security requirement," according to one Department of Homeland Security investigator interviewed by the FBI.

An FBI records administrator told interviewers in the Clinton investigation that he believed the State Department was attempting to minimize political fallout for Clinton.

The official, whose name is redacted in FBI interview notes, "believes STATE has an agenda which involves minimizing the classified nature of the CLINTON emails in order to protect STATE interests and those of Clinton."

In a Sunday story on the interview notes, the Weekly Standard reported that Undersecretary of State Patrick Kennedy arranged a "quid pro quo" to give additional overseas postings to the FBI if officials there retroactively changed the classification designations of some Clinton emails.

Clinton told the FBI that she does not pay attention to the specific classified markings on information in her possession.