An email containing the name of a source of the Central Intelligence Agency was sent to then-Secretary of State Hillary Clinton on the private server she used to conduct government business, according to Trey Gowdy, the Republican chairman of the House select committee investigating the 2012 Benghazi attacks said on Thursday.

The message's sender was Sidney Blumenthal, and it apparently contained highly sensitive information that the Clinton confidant had received from Tyler Drumheller, a former top CIA official with whom Blumenthal had a business relationship, Yahoo News reported based on email excerpts released by Gowdy.

Blumenthal apparently suggested President Barack Obama backed military intervention in Libya in 2011 to help boost his own poll numbers. He also lobbied on behalf of a company run by an associate that provided training for rebels fighting the regime of Col. Muammar Gaddafi, Fox News noted. At the time, Blumenthal was not a government employee, but still sent Clinton a steady stream of emails full of foreign policy advice, the news channel added.

"It is curious Secretary Clinton took so much of her advice from someone who had never been to Libya, professed no independent knowledge of the country and who the White House blocked her from hiring," Gowdy said in a statement Thursday. "Any one of those should have been a red flag, but instead, she continued to solicit Blumenthal for advice."

The sensitive nature of the contents of Blumenthal's messages should have raised concerns with Clinton, and the emails should never have been passed along, John Maguire, a former veteran CIA officer who served for years as one of the agency's top Mideast officers, told Yahoo News.

"She is exposing the name of a guy who has a clandestine relationship with the CIA on her private, unprotected server," Maguire noted.

But Clinton campaign spokesman Brian Fallon dismissed Gowdy's revelations as a political stunt intended to harm the Democratic front-runner's 2016 presidential aspirations.

"Trey Gowdy continues to release selective and misleading information about emails sent to Hillary Clinton," Fallon said, "even as he refuses to make public any of the transcripts from the closed-door witness interviews that actually relate to Benghazi."