Rep. Jason Chaffetz (R., Utah) remains intent on finishing the investigation into Hillary Clinton's private email server and lambasted the State Department on Wednesday for delaying the release of relevant documents.

"We need to understand the gravity of this. There is a reason the State Department, years after, is still holding off on giving us documents," Chaffetz told Fox News. "The more they want to hold them, the more curious we are on what's in them."

Chaffetz, who chairs the House Oversight and Government Reform Committee, has committed to further probe Clinton's email activity even after she lost the presidential election to Donald Trump.

So pleased she is not the President. I thanked her for her service and wished her luck. The investigation continues. A post shared by Jason Chaffetz (@jasoninthehouse) on Jan 20, 2017 at 12:31pm PST

Chaffetz said he believes the investigation will continue well into 2018 and charged that up to 300 people at the State Department may have mishandled classified information.

He called the department "dreadfully slow" in turning over about 30,000 additional documents relevant to the probe.

The FBI investigated Clinton's email practices last year to determine if she mishandled classified material over her private server while serving as secretary of state. The agency eventually recommended that no criminal charges be filed against Clinton. The Justice Department said that it accepted the FBI's findings.

Chaffetz has repeatedly pushed to continue the investigation following President Trump's inauguration. On Feb. 16, the Utah Republican sent a letter to Attorney General Jeff Sessions asking the Justice Department to prosecute Bryan Pagliano, a former State Department IT technician who set up Clinton's private email server in her home.

Pagliano failed to comply with multiple congressional subpoenas.

The letter was attacked by the top Democrat on the House Oversight Committee, Rep. Elijah Cummings (D., Md.), who said Chaffetz's efforts were a waste of time and resources.