Rep. Steve Russell, R-Okla., said Thursday that the undisclosed records recovered and produced by the FBI during its year-long investigation of Hillary Clinton's private server are much more shocking than the summary report released last week.

"If what I've read in the vaults about Secretary Clinton's mishandling of classified information were known to the American people, as I've been to the vaults to peruse them, the American public would be absolutely appalled," Russell said during a House Oversight Committee hearing on the State Department's treatment of records requests.

"But we can't talk about that," he said, noting many details surrounding Clinton's email server remain highly classified.

"Instead of focusing on this mishandling and its subsequent obfuscation ... we are now seeing a typical play: admit nothing, deny everything and make counteraccusation," Russell added.

The 58 pages of notes made public by the FBI on Friday suggested Clinton and her aides took dramatic steps to conceal emails during and after their State Department tenure, including the destruction of mobile devices with a hammer and the deletion of records covered by a congressional subpoena.

Clinton has continued to defend her conduct, conceding that her private email use was "a mistake" but denying that she broke any laws.

The FBI has provided an undisclosed number of records to Congress. Some of those documents, including emails recovered from Clinton's server, are so highly classified that only members of the intelligence committees can view them. Other records can only be viewed in secure areas known as SCIFs.