Former US president Donald Trump can be heard discussing secret documents he had apparently held on to and acknowledging he had not declassified them in an audio recording aired by CNN.

The two-minute recording comes from an interview Trump gave at his Bedminster, New Jersey, golf club in July 2021 for people working on a memoir by his former chief of staff Mark Meadows.

Parts of a transcript of the recording were cited as evidence in special counsel Jack Smith’s 49-page indictment of Trump on charges he had mishandled classified documents after leaving office.

The audio file played by CNN late on Monday, and also obtained by ABC and CBS, includes a moment when Trump seems to indicate he is holding a secret Pentagon document with plans to attack Iran.

“These are the papers,” Trump says in the recording, a quote that was not included in the indictment.

He also refers to something as “highly confidential” and “this is secret information” as he seems to be showing something to the others in the room.

“This was done by the military and given to me,” Trump continues, before noting that the document remained classified.

“You see, as president I could have declassified it. Now I can’t, you know,” he says.

“Now we have a problem,” one of his staff responds.

“Isn’t that interesting? It’s so cool,” Trump says, and the recording ends with him calling for someone to bring in some Cokes.

Trump earlier this month pleaded not guilty on 37 counts of wilfully mishandling US government secrets and conspiring to prevent their return, becoming the first US president to face criminal charges.

The Department of Justice (DoJ) accuses Trump — who is vying to win back the White House next year — of violating the Espionage Act and other laws when he removed classified documents upon leaving office and failed to give them up to the National Archives.

In its indictment, the DoJ described evidence including an audio recording from a July 2021 meeting that Trump, who was no longer president, had with an author, a publisher and two of his staff — none of whom had a US security clearance — in which Trump showed them what he called a “secret” and “highly confidential” document.

The pugnacious 77-year-old billionaire is accused of willfully hoarding dozens of classified documents he took unlawfully to his beachfront mansion in Florida, refusing to return them and conspiring to obstruct investigators seeking their recovery.

Trump is also accused of sharing sensitive US secrets with people who had no security clearance.

His criminal trial is tentatively scheduled to begin on August 14, but his legal team is likely to get the preliminary date pushed back by months.