Bryan Pagliano, an IT specialist who worked for the US State Department under Hillary Clinton, appears to have warned his bosses that the email server which the then-secretary of state used was not secure and could have violated US laws, the FBI records reveal.

Pagliano, who refused to testify before Republican lawmakers in Congress, revealed to the FBI investigators that two staffers from the department’s IT office had contacted him upon getting familiar with the email system in 2009, saying it could see troubles with “federal records retention.”

One of the technicians also said to Pagliano that “he wouldn't be surprised,” if he learned that Clinton was sending classified data through her private email system, according to the FBI’s interrogation papers.

Prompted to raise concerns with Clinton’s "inner circle," Pagliano turned to Cheryl Mills, who served at the time as secretary of state’s chief of staff.

Mills, being interrogated under oath earlier, denied that she had been told about possible problems with the system.

The shocking revelation came on Friday as the FBI published 200 pages of its records that summarize the agency’s year-long probe into Clinton’s use of the personal email system during her term in the Department of State.

Earlier on Thursday, Pagliano was voted to be held "in contempt of Congress" by US lawmakers for failing to report to a congressional hearing under subpoena from the US House of Representatives.

In June, he refused to answer questions from the conservative group Judicial Watch that continues to examine the contents of Clinton’s emails.

The FBI records also revealed that during the investigation senior State Department officials pushed to conceal the information about classified data to whitewash Clinton’s potential wrongdoings.

An unnamed State Department staffer, who worked on the screening of the emails during the probe, told investigators that Clinton had correspondences stacking up to over 1,000 emails with David Petraeus, the director of the United States Central Command at the time. Only ten of them were made public, however, when the Pentagon released them last year.

State Department spokesperson John Kirby denied allegations of official meddling in the screening process, saying he couldn’t speculate about whether the Pentagon had discovered more classified emails.

The email scandal has undermined Clinton’s presidential candidacy raising concerns over her ability to run the country. She acknowledges that the use of her a private email system was a mistake.