Federal Judge Aileen Cannon also appointed Senior District Judge Raymond Dearie as a third party to review records seized by the FBI for materials that could be privileged and kept from federal investigators.

The Justice Department has promised to take the case to an appeals court if Cannon ruled against their request. They had also sought to block the independent arbiter, Dearie, from vetting the roughly 100 classified documents included among the 11,000 records gathered in the court-approved Aug. 8 search.

"The court does not find it appropriate to accept the government’s conclusions on these important and disputed issues without further review by a neutral third party in an expedited and orderly fashion," Cannon wrote Thursday.

A Justice Department spokesperson and Trump's attorneys did not immediately return requests for comment.

Cannon's ruling further complicates the Justice Department's investigation. The special master's review could wall off documents from prosecutors as they weigh the possibility of criminal charges.

Cannon on Thursday said she would instruct Dearie to prioritize reviewing the classified records first. She also directed him to complete his review of all the seized materials by Nov. 30.

The Justice Department is investigating Trump for retaining government records - some marked as highly classified, including "top secret" - at his Mar-a-Lago estate in Palm Beach after leaving office in January 2021.

The department also is looking into possible obstruction of the probe after it found evidence that records may have been removed or concealed from the FBI when it sent agents to Mar-a-Lago in June to try to recover all classified documents through a grand jury subpoena.

The documents inquiry is one of several federal and state investigations that Trump is facing as he considers another run for the presidency in 2024.

The Justice Department on Sept. 8 asked the judge to partially lift her prior restriction banning its investigators from reviewing all of the documents seized last month at Mar-a-Lago so they could at least continue scrutinizing the ones marked as classified.

They also asked the judge to exclude those classified records from the scope of the special master's review, vowing to appeal to the Atlanta-based 11th U.S. Circuit Court of Appeals if she did not.

Trump's attorneys opposed both requests, telling the judge in a Monday filing they dispute the government's claim that all the records are classified, and that a special master is needed to help keep prosecutors in check.

Trump's lawyers in Monday's filing disputed the department's claim that the roughly 100 documents at issue are in fact classified, and they reminded Cannon that a president generally has broad powers to declassify records. They stopped short of suggesting that Trump had declassified the documents, a claim he has made on social media but not in court filings.

About two weeks after the search, Trump's attorneys sought the appointment of a special master to review the seized records for materials that could be covered by attorney-client privilege or executive privilege - a legal doctrine that can shield some presidential records from disclosure.

In ruling on Sept. 5 in favor of Trump's request, Cannon rejected Justice Department arguments that the records belong to the government and that because Trump is no longer president he cannot claim executive privilege. Cannon was appointed to the bench by Trump in 2020.