US Magistrate Judge Bruce Reinhart on Thursday gave the Justice Department one week to propose what information in the document should be kept secret.

“I’m not prepared to find that the affidavit should be fully sealed,” Reinhart said during a hearing on a request from news media organisations and others to publicly release the affidavit.

Reinhart made the remarks moments after Jay Bratt, the Justice Department’s counterintelligence chief, told him that an ongoing investigation would be “severely compromised” if the affidavit is released, adding that a line-by-line redaction of the document was unrealistic.

The Justice Department and Trump agreed last week to release the warrant and other documents which described the items seized during the August 8 search as well as the laws that may have been violated. But the government said the more detailed affidavit contains information, especially about witnesses, that needs to be protected while the investigation is ongoing.

Trump, who claims the search was politically motivated and unnecessary, did not file a motion seeking to unseal the affidavit, despite saying in public statements that the judge should do so.

One of Trump’s attorneys, Christina Bobb, attended the court hearing Thursday and declined to comment, other than to say Trump wants the affidavit unsealed.

Reinhart’s ruling on Thursday came in the first public hearing stemming from the unprecedented search of a former president’s residence, from which Federal Bureau of Investigation (FBI) agents took 11 sets of classified documents.

The affidavit – typically a detailed explanation of an ongoing probe – would likely shed more light on why Reinhart approved the politically explosive search less than three months before the midterm elections. Trump and his allies have fiercely attacked the judge, FBI and Justice Department over the search.

The Justice Department argued in an August 15 court filing that keeping the affidavit sealed would “protect the integrity of an ongoing law enforcement investigation that implicates national security”. Unsealing the affidavit could also reveal “highly sensitive information” about witnesses, the government said.

Some Republican legislators had also called for the release of the document while Senate Intelligence Committee leaders made a bipartisan request to the government for members to privately access the classified documents.

(Reporting by Erik Larson.)