Hillary Clinton withheld Benghazi-related emails from the State Department that detailed her knowledge of the scramble for oil contracts in Libya and the shortcomings of the NATO-led military intervention for which she advocated.

Clinton removed specific portions of other emails she sent to State, suggesting the messages were screened closely enough to determine which paragraphs were unfit to be seen by the public.

For example, one email Clinton kept from the State Department indicates Libyan leaders were "well aware" of which "major oil companies and international banks" supported them during the rebellion, information they would "factor into decisions" about about who would be given access to the country's rich oil reserves.

The email, which Clinton subsequently scrubbed from her server, indicated Clinton was aware that involvement in the controversial conflict could have a significant financial benefit to firms that were friendly to the Libyan rebels.

She thanked Sidney Blumenthal, her former aide and author of dozens of informal intelligence memos, for the tip, which she called "useful," and informed him she was preparing to hold a meeting with Libyan leaders in Paris in an exchange that suggests the flow of information went both ways.

State Department officials admitted Clinton had withheld all of nine emails and parts of six others after Blumenthal provided 60 emails to the House Select Committee on Benghazi that the agency had failed to submit earlier this year.

Chairman Trey Gowdy, R-S.C., immediately demanded to know whether State or Clinton herself withheld the records. The agency's admission Thursday that it couldn't find 15 of the new emails in its records indicated both had played a role in keeping the emails away from Congress.

An undisclosed memo sent in February 2012 contains details about how new Libyan leaders were forging business relationships with private firms. Blumenthal told Clinton his sources were concerned about the focus of international interest on Libya's oil sector, playing up the importance of other "private firms" that could provide "medical assistance."

By his own admission, Blumenthal had a personal financial interest in Libya involving medical assistance.

The fact that Clinton held the email back raises questions about whether she was aware of the conflict of interest at play in Blumenthal's advocacy.

Clinton also declined to hand over a memo in which Blumenthal relayed the complaints of Libyan rebels who felt NATO wasn't going far enough in its assistance in their struggle against Gaddafi.

"[R]ebel military commanders are extremely frustrated by the performance of NATO air forces over the weekend of April 22 [2011]," Blumenthal said.

"At the same time, these commanders believe that the small number of tactical advisers sent by Great Britain and France, under their NATO mandate, is not equipped to deal with the scope of the challenge facing the rebels," he added.

Blumenthal said his sources believed the U.S. could better support the rebels by sending traditional aircraft, such as A-10 "Warthogs," to combat the regime instead of the Predator drones it deployed after NATO took the lead in the mission.

The reason why Clinton withheld that particular memo is unclear, but it demonstrates that she knew the coalition's efforts were falling flat — and that they could have been boosted if she pushed for the use of a less politically popular aircraft.

Clinton withheld an email sent March 22, 2011 that described the French government's alleged involvement in forming the transitional government as the uprising against Gaddafi raged.

In the email, Blumenthal claimed the French had "provided money and guidance to assist" with the emerging Libyan council.

"In return for this assistance, [French government] officers indicated that they expected the government of Libya to favor French firms and national interests, particularly regarding the oil industry in Libya," Blumenthal wrote.

An email in which Blumenthal encouraged Clinton to consider the same "shock-and-awe" tactics former President George W. Bush employed in Iraq was also not included among the emails Clinton provided to State.

Blumenthal openly pressed for an increase in U.S. funding in another email that Clinton refused to turn over.

"My own view is that they desperately need professional military trainers, preferably Americans," Blumenthal said.

"Some of the funds released should go to that end," Blumenthal added, referring to the creation of a "more professional military" in the aftermath of the Gaddafi regime.

In the same memo, Blumenthal assured Clinton that representatives of the country's transitional government were "very, very happy," about a meeting with the secretary of state in May of 2011.

The subject of the same email refers to a "memo on OBL photos," likely referring to photographs of slain terrorist leader Osama bin Laden, who was killed days before Blumenthal sent the memo. A controversy over whether the government should release graphic pictures of bin Laden continues to this day.

In the subject, Blumenthal said there was "more to come soon on Libya," but he did not send another email until the following month. The gap raises additional questions about whether Blumenthal provided Congress with all the emails he and Clinton exchanged.

Clinton selectively edited other portions of emails she declined to provide to the State Department.

For example, in July 2012, Clinton removed paragraphs from a Blumenthal memo that warned "simply completing the election...and fulfilling a list of proper democratic milestones may not create a true democracy." Blumenthal also wrote — in sections that Clinton deleted before providing the document to State — that the government would likely be "founded on Sharia," or Islamic laws.

The group advocating to implement Sharia, Ansar al-Sharia, is a designated terrorist group that played a role in the Benghazi attacks.

But Clinton hid how much she knew about that development.

Clinton withheld another email that showed she informed Blumenthal of a "very good call" she had with the new Libyan president, Mohammed Yussef el Magariaf. She deleted another, in which she called a memo about Magariaf's intention and history "a keeper."

Clinton did not include in the batch published by the State Department last month an exchange in which she prompted Blumenthal to provide her with "more intel" about French and British involvement with Libyan leaders.

She told Blumenthal the memo "strains credulity" in a message she withheld from State. Clinton posed the same question to a top aide, Jake Sullivan, when she forwarded him the memo, according to the records released by the agency.