Fox News contributor Marc Thiessen said on Monday that former FBI Director James Comey issued “a non-apology apology” during his interview on "Fox News Sunday,” in which Comey said the recently released Justice Department Inspector General’s report on the launch of the FBI’s Russia investigation and their use of the surveillance process showed that he was "overconfident" when he defended his former agency's use of the Foreign Intelligence Surveillance Act (FISA).

“He essentially said, ‘Well we were sloppy,’” Thiessen, a former White House speechwriter, said on “America’s Newsroom” on Monday morning.

“No, you weren't sloppy," Thiessen said. "The inspector general found the FBI falsified evidence in the FISA process.”

COMEY ADMITS 'I WAS WRONG' ON FISA CONDUCT, REMAINS DEFIANT ON DOSSIER IN TENSE INTERVIEW

“How do you accidentally falsify evidence?” Thiessen asked. “It can’t. It has to be intentional, it’s not sloppy.”

Comey’s interview on “Fox News Sunday” came days after Inspector General Michael Horowitz’s report and testimony before the Senate Judiciary Committee detailed concerns that included 17 “significant errors and omissions” by the FBI’s investigative team when applying for a FISA warrant to monitor former Trump campaign adviser Carter Page. Horowitz referred “the entire chain of command” to the FBI and DOJ for “how to assess and address their performance failures” during the probe, which was conducted while Comey was in charge.

"He's right, I was wrong," Comey said about how the FBI used the FISA process, adding, "I was overconfident as director in our procedures," and that what happened "was not acceptable."

Comey, however, remained defiant on former British spy Christopher Steele’s anti-Trump dossier, which served as the basis for FISA warrants against Page. Horowitz’s report stated that government attorneys were hesitant to approve a FISA warrant application until they relied on unverified information from Steele. That information also was used in subsequent renewals for the FISA warrant.

IG HOROWITZ RIPS FBI 'FAILURE IN RUSSIA PROBE, SAYS NOBODY VINDICATED BY REPORT

“Comey told the American people repeatedly that the Steele dossier was not essential to the FISA warrants,” Thiessen said on Monday.

He added, “The inspector general found that it quote ‘played a central and essential role in getting the FISA warrants.’ In other words, if it had not been for the Steele dossier, there would have been no FISA warrant, there would have been no surveillance. So James Comey has a lot of explaining to do and he didn't do a good job of it on Sunday.”

On Monday morning, Thiessen also referenced U.S. Attorney John Durham, who is conducting a wide-ranging investigation of the origins of the Trump-Russia probe. Durham released a rare statement last week saying he disagrees with conclusions of the so-called FISA report that the probe's launch largely complied with the Department of Justice and FBI policies.

“We spent two-and-a-half years, tens of millions of dollars chasing a conspiracy theory that Donald Trump had somehow colluded with Russia to steal the election and it turned out it wasn't true,” Thiessen said on “America’s Newsroom.”

CLICK HERE FOR THE FOX NEWS APP

“Americans want to get to the bottom of how that happened and James Comey was at the center of it and we're going to see from John Durham whether there was bias in the FBI or not.”

Fox News’ Ronn Blitzer contributed to this report.