The State Department has opened a formal probe into former Secretary of State Hillary Clinton and her aides to determine whether they mishandled classified information with their email practices while serving in government.

The department's investigation seeks to determine whether Clinton or her aides violated government procedure by using her private email server to send and receive classified information, Fox News reported Tuesday.

Clinton and her top aides still have security clearances to access sensitive information despite being under investigation.

Sen. Chuck Grassley (R., Iowa), chairman of the Senate Judiciary Committee, confirmed to Fox News the investigation into Clinton and her staff.

The investigation comes after the FBI determined in July 2016 that Clinton and her aides at the State Department were "extremely careless" with their handling of classified information. Still, then-FBI Director James Comey recommended that the Justice Department should bring no criminal charges against Clinton, arguing that the former Democratic presidential candidate did not have the intent to commit criminal activity.

The Senate Judiciary Committee in March launched a separate investigation into Clinton's handling of government emails.

Clinton and her top aides could have their security clearances revoked pending the outcome of the investigation.

Clinton spokesman Nick Merrill told Fox News that the investigation into Clinton's potential mishandling of classified information is done.

"Nothing's been more thoroughly dissected. It's over. Case closed. Literally," Merrill said.