The FBI has found a document describing a foreign government's nuclear capabilities while it was searching former US President Donald Trump's residence, according to the Washington Post.
The paper added that some of the documents recovered required special clearances, beyond even a top-secret clearance.
The FBI raided Trump's Mar-a-Lago estate on August 8th, recovering more than 11,000 government files, according to court records.
Trump has hit back at the FBI and Department of Justice - calling them “vicious monsters” and claiming to have de-classified all the documents.
On Monday a federal judge agreed to Trump's request to appoint an arbiter, or “special master”, to review the records seized during the search and ensure none are subject to executive privilege or attorney-client privilege.
That will bar the Department of Justice from using the files for to further the investigation until the review is complete.