The Department of Justice has released documents used by the government to justify the FISA surveillance warrant against Carter Page, a former campaign adviser to then-candidate Donald Trump.

The materials released by the DOJ include an October 2016 application to the Foreign Intelligence Surveillance Court to wiretap Page as well as several renewal applications. It is highly unusual for documents related to FISA wiretap applications to be released.

Though heavily redacted, the documents show that the infamous and unverified Steele Dossier was a major component of the 2016 surveillance warrant. The dossier, which was opposition research funded by the DNC and Hillary Clinton campaign, contains salacious allegations against Trump. It was also a major component used to justify subsequent renewals.

The visible sections of the released FISA documents do not indicate the dossier was ever verified. Instead, the FBI claimed that Steele was “reliable” based on his previous work.

The FISA records also reveal that a September 2016 Yahoo News article by Michael Isikoff was a significant part of the government's warrant application.

But London court records show, and Republicans emphasize, that Steele briefed Yahoo News and other reporters in the fall of 2016 at the direction of Fusion GPS -- the opposition research firm behind the Steele Dossier.

WATCH: DARRELL ISSA REACTS TO RELEASE OF FISA DOCUMENTS

The newly released FISA warrant application, however, seems to indicate the Yahoo News article was an independent piece of corroborating information that justified the surveillance of Carter Page. Republicans question whether the story is an example of circular reporting that merely repeated information from Fusion GPS, the opposition research firm that commissioned former British spy Christopher Steele to compile the dossier.

Based on what is visible, the dossier is not described to the FISA court as a political document, as the Democrats have asserted; in fact, the FBI speculates to the FISA court that it was commissioned to damage Candidate 1, who is Donald Trump.

Page's denials of the Yahoo News reporting were included in the early renewals to the FISA application. The last renewal in late Spring 2017 is particularly important, because by that point, the FBI had dumped Steele as a source after he misled them over his media contacts.

One of the documents reads: “The FBI speculates to the FISA court that the U.S. person was likely looking for information that could be used to discredit candidate 1’s campaign."

Fox News believes that the U.S. person is Glenn Simpson, co-founder of Fusion GPS.

HOUSE MEMO: DISPUTED DOSSIER KEY TO FBI FISA WARRANT TO SURVEIL TRUMP TEAM

The unredacted FISA materials also contain only limited references to ex-Trump adviser George Papadopoulos. Media reports had speculated that Papadopoulos' 2016 meeting in London with a professor who had ties to Russia was a key justification for the FISA-authorized surveillance of Page.

Papadopoulos has since pleaded guilty to lying to federal investigators in Special Counsel Robert Mueller's probe.

Critics have charged that Deputy Attorney General Rod Rosenstein, who signed off on the FISA application renewals, should not have approved them without more reliable intelligence.

Reacting to the document release, Page told Fox News, "I'm having trouble finding any small bit of this document that rises above complete ignorance and/or insanity."

President Trump also weighed in on Twitter Sunday, calling the situation a "scam."

"Looking more & more like the Trump Campaign for President was illegally being spied upon (surveillance) for the political gain of Crooked Hillary Clinton and the DNC," Trump wrote. "Ask her how that worked out - she did better with Crazy Bernie. Republicans must get tough now. An illegal Scam!"

The surveillance of Page became a contentious matter between Republican and Democratic lawmakers earlier this year. Republicans alleged the FBI had abused its surveillance powers and improperly obtained the warrant, a charge that Democrats rebutted as both sides characterized the documents in different ways. The documents, meanwhile, remained out of public view.

WATCH: CARTER PAGE SPEAKS OUT

House Democrats were quick to say that the documents bolstered their arguments.

"For more than a year, House Republicans have bullied the Department of Justice and FBI to release highly sensitive documents to derail the Special Counsel's and other legitimate national security investigations and cover for the President," House Democratic leader Nancy Pelosi said in a statement. "For the sake of our national security and our democracy, these vital investigations must be allowed to continue unhindered by Republican interference. The GOP must cease their attacks on our law enforcement and intelligence communities, and finally decide where their loyalty lies."

U.S. Rep. Adam Schiff, the California Democrat who is the ranking member of the House Intelligence Committee, said the documents underscore the "legitimate concern" the FBI had about Page's activities. Yet Schiff said the materials shouldn't have been released during an ongoing investigation because of national security.

Schiff blamed Trump for making public the House Republicans' initial memo about the FISA applications, a move by Trump that the congressman called "nakedly political and self-interested, and designed to to (sic) interfere with the Special Counsel's investigation."

Earlier this year, GOP members of the House Intelligence Committee voted to release a memo claiming the DOJ abused the FISA warrant process in order to hurt Trump's presidential campaign, claiming the warrant against Page was based in significant part on the Steele Dossier.

Trump declassified the memo over the objections of the FBI, which warned that the document contained “material omissions of fact that fundamentally impact the memo’s accuracy,” the Hill report said.

Fox News' Gregg Re and the Associated Press contributed to this story.