A memo Sidney Blumenthal forwarded to his friend Hillary Clinton when she was secretary of state contained information classified as SECRET both when he sent it and currently, the FBI’s Clinton email investigation report says.

It was already known that about two dozen of the hundreds of emails Blumenthal sent Clinton during her tenure contained classified information. (RELATED: Here Are The Classified Memos Sidney Blumenthal Sent To Hillary)

But the FBI’s report, released Friday, reveals for the first time that one of the emails contained information the government considers to have been classified as soon as it hit Clinton’s inbox.

Clinton and the State Department have downplayed the presence of classified information in her emails by pointing out that most of the information has been classified retroactively through a process called “up classification.”

“When information is reviewed for public release, it is common for information previously unclassified to be upgraded to classified if the State Department or another agency believes its public release could cause potential harm to national security, law enforcement or diplomatic relations,” reads an entry on Clinton’s campaign website defending the presence of “up classified” emails in her records.

The FBI’s report states that 24 Blumenthal memos have been identified as containing “information currently classified as CONFIDENTIAL.” But one April 23, 2010 email has been deemed to contain information that is “SECRET both when sent and currently.”

The email is entitled “Important new memo on Kyrg” and provides updates on Kyrgyzstan following a a revolution there on April 7, 2010.

[dcquiz] “[Redacted], my friend with deep contacts in Kyrgyzstan and who testified this week on the latest developments there before the House Oversight Committee, has sent me a memo containing important new information and including some recommendations,” Blumenthal wrote to Clinton in the message.

The portion redacted as SECRET/NOFORN discusses a criminal investigation of some sort. The government’s rationale for the redaction is that the information involves “foreign relations or foreign activities of the United States, including confidential sources.”

The government classifies information as SECRET when its unauthorized disclosure “reasonably could be expected to cause exceptionally grave damage to the national security.” The NOFORN marking indicates that the information — which will be declassified in 2035 — cannot be shared with foreign governments.

Blumenthal’s correspondent appears to have been Scott Horton, an international lawyer and human rights activist with expertise in Central Asia.

Horton testified in the House Oversight Committee hearing Blumenthal referenced in his email to Clinton. And Horton, who is also an adviser to left-wing billionaire George Soros’ Open Society Institute, sent Blumenthal other emails regarding Kyrgyzstan which were forwarded to Clinton.

Horton was in full support of the Kyrgyz revolution, which led to the overthrow of president Kurmanbek Bakiyev.

“I was involved with them,” he told the NYC Bar of the leaders of the interim government who overthrew Bakiyev.

“And now we jump forward fifteen years, and learn that many of the people who worked with us setting up the bar colloquium played central roles in the recent revolution!” Horton added in that interview.

He had met several leaders of the Kyrgyz revolution, the second in five years, while he served on the New York City Bar’s International Human Rights Committee in the 1990s.

In his House Oversight testimony, Horton said that the revolution commenced because of widespread public corruption. Bakiyev and his family were enriching themselves through shady gas contracts, Horton testified.

Horton did not respond to an emailed request for more detail about his email to Blumenthal and whether he agreed with the government’s assessment that the information is highly classified. But the lawyer-activist has weighed in elsewhere on the issue of Clinton’s classified emails.

In an article for Harper’s magazine last August, Horton argued that the government routinely over-classifies information.

It’s clear from the article that Horton believes the scandal has been much ado about nothing.

“Is the Clinton email controversy a bona fide political scandal or more of the sort of makeweight distraction that tends to dominate American political reporting when presidential elections roll around?” he asks. “That’s a question that will play out over the coming weeks—and the answer will depend to a great extent on what’s actually in those emails that are being gossiped about but not really reported on in any meaningful way.”

Horton, who is a managing editor at Harper’s, did not disclose in that article that he corresponded with Blumenthal — who is referred to only as Clinton’s “confidant.” He also did not disclose that he sent Blumenthal an email containing highly classified information. It’s unclear if Horton knew at that time that the government had deemed the email to contain SECRET information. The memo was released by the State Department last December, several months after Horton’s article was published.

The Horton memo is not the first one supporting regime change that Blumenthal forwarded to Clinton while she was in office. The former journalist and Bill Clinton White House aide sent Clinton numerous emails in 2011 pushing for the ouster of Libyan dictator Moammar Gaddafi. Blumenthal was working with a small group of former military officials and a retired CIA operative who were seeking defense contracts in a post-Gaddafi Libya.

Clinton was the Obama administration’s most vocal supporter of Libyan regime change. She has been heavily criticized for pushing for Gaddafi’s removal without a thorough plan to replace him. Portions of the north African nation have fallen under control of terrorist groups like ISIS and al-Qaida.

Follow Chuck on Twitter