The State Department does not appear to have submitted legally required information regarding Hillary Clinton's secret computer server to the Department of Homeland Security during her term as secretary, FoxNews.com has learned. 

All federal government agencies are mandated to submit a list of systems, vulnerabilities and configuration issues to DHS every 30 days. The department then performs a "cyberscope audit" to ensure security, a responsibility the agency has had since 2010. 

FoxNews.com learned of the lapse as a result of a Freedom of Information Act request submitted June 11. It is not clear if State Department officials in charge of compliance with the DHS audits knew of their boss's server, which has been shown to have included "top secret" information in emails. 

Clinton headed the agency from 2009-2013. The DHS established the "Continuous Diagnostics and Mitigation" program in 2010, amid growing concerns government systems could be vulnerable to cyber attack. But Clinton's computer server, through which she and key aides sent and received tens of thousands of emails, was apparently never audited, according to DHS, which conducted a comprehensive search of Office of Cyber Security and Communications records after FoxNews.com lodged its request. 

"Unfortunately, we were unable to locate or identify any responsive records," wrote Sandy Ford Page, chief of Freedom of Information Act operations for DHS. 

The revelation means DHS never audited Clinton's server, and the State Department allowed Clinton to operate outside the federal mandate aimed at hardening defenses in federal networks, one cyber expert told Fox News. 

The latest headlines on the 2016 elections from the biggest name in politics. See Latest Coverage →

The State Department has not provided a substantive response to a similar FOIA submitted by FoxNews.com in early June. 

The State Department did not comment on media requests about why it did not comply with the DHS security review requirement. 

"There are reviews and investigations under way, including by the IG and Congress," said State Department Spokesman Alec Gerlach. "It would not be appropriate to comment on these matters at this time." 

Denver-based Platte River Networks upgraded and maintained the server Clinton shares with her husband, former President Bill Clinton, after she left the State Department. 

The company is not on the list of contractors approved by the Pentagon's Defense Security Service, the only federal agency with the authority to review and approve private contractors. The department administers the National Industrial Security Program on behalf of the Pentagon and 30 other federal agencies, including the State Department. About 13,000 companies have received clearance. 

"But Platte River is not one of them," a spokesman for the DSS told Fox News. "As Platte River Networks is not a cleared facility under the National Industrial Security Program, DSS has no cognizance over the facility and cannot comment further." 

Clinton, the leading contender for the 2016 Democratic presidential nomination, and the State Department have been under fire in recent months after it was revealed Clinton had a "homebrew" server and private Blackberry system that could have left classified or sensitive government data open to hackers. 

Clinton maintains her use of a private email server was allowed under government regulations and her system was secure. 

But this followed the news Clinton wiped her server of some 31,000 private email messages, turning over just 30,000 hard copies of her emails to the State Department amid a congressional investigation into her actions during the Sept. 11, 2012 attack on the U.S. consulate in Benghazi, where four U.S. personnel including the U.S. ambassador to Libya were killed. 

While Clinton has maintained that she neither sent nor received information marked classified on her private server or Blackberry, Reuters reported last week that dozens of emails that passed through Clinton's server while she was secretary of state, under the U.S. government's own regulations, were automatically considered classified. 

That includes 30 email threads starting as early as 2009, which contained information on foreign governments, Reuters said. 

The FBI has opened an investigation to determine whether or not Clinton's private email server was secure and if classified material was improperly shared or stored on the Clintons' private email account. 

A federal court hearing last week only added to the intrigue. The State Department asserted in a court filing that it did not give personal electronic devices to Clinton and may have destroyed the smartphones of her top aides, Huma Abedin and Cheryl Mills. 

"If the State Department was not providing secure email devices to Mrs. Clinton, who was? Best Buy? Target? Mrs. Clinton clearly did whatever she wanted, without regard to national security or federal records keeping laws," said Judicial Watch President Tom Fitton, who took the State Department to court over its lack of disclosure on the email and server issues.