Former US president Donald Trump is being investigated for potentially violating the Espionage Act and obstructing justice, an unsealed FBI search warrant showed on Friday.
The warrant also says the bureau is investigating Mr Trump for the removal or destruction of records.
It states “property to be seized” at Mr Trump's Mar-a-Lago resort in Palm Beach, Florida, included “all physical documents and records constituting evidence, contraband, fruits of crime or other items illegally possessed in violation of” the crimes being investigated.
On Monday, federal agents searched Mar-a-Lago and the unsealed warrant states the FBI removed about 20 boxes from the premises.
There were 11 sets of classified documents taken, including one box labelled "Various classified/TS/SCI documents," which refers to information that requires the highest level of security clearance to obtain.
"SCI" documents are "sensitive compartmented information," or some of the nation's most sensitive material that mandates protection in approved settings or facilities.
The Espionage Act, which Mr Trump is being investigated for, prohibits possessing national security information that could be used against the country or aid a foreign adversary.
It poses a prison sentence of up to ten years.
Additionally, there were four boxes that included “miscellaneous top secret documents” and three with “confidential documents”.
Another included “info re: President of France”.
The Washington Post reported that there were concerns that documents relating to US nuclear weapons were being held in Mar-a-Lago.
“I personally approved the decision to seek a search warrant,” US Attorney General Merrick Garland confirmed in a news conference on Thursday, when he also stated he had formally requested the unsealing of the warrant.
The US Department of Justice on Friday said Mr Trump did not object to the public release of the FBI warrant.
He posted on his Truth Social media platform on Thursday that he was “encouraging the immediate release of those documents”.