(CNN) The FBI on Saturday released a redacted version of its previously classified foreign surveillance warrant application on Trump campaign foreign policy adviser Carter Page, which has been the subject of a heated partisan debate over the FBI's tactics investigating members of the Trump campaign.

The FBI released the Foreign Intelligence Surveillance Act warrant application after news organizations and advocacy groups like Judicial Watch sued for its disclosure.

The warrant, which was approved for Page in 2016, allowed the FBI to conduct surveillance on Page. It's been one of the key moves that Republicans have charged is evidence of a pattern of abuse by the Justice Department and the FBI targeting the Trump campaign.

The release itself is significant as it marks the first public disclosure of a highly sensitive FISA request. Information included in the request had been largely reported through two declassified memos released separately by Republicans and Democrats on the House Intelligence Committee, but Saturday's disclosure puts the FBI's own argument in black and white for the first time.

The more than 400-page document released Saturday, which includes the initial October 2016 FISA warrant on Page and three subsequent renewals, is heavily redacted.

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