US prosecutors have told Donald Trump's lawyers that he is the target of a probe into his handling of classified documents after leaving the presidency, in a sign he might be indicted, US media reported Wednesday night.

The notice came from the office of special counsel Jack Smith, The New York Times, CNN and other new outlets said, and gives the clearest sign yet that prosecutors are moving closer to charging the former president, who has already been indicted in a separate case.

The Times, citing "two people familiar with the matter," said it was not clear when Trump's team had been told he was a target.

A special counsel named by Attorney General Merrick Garland has been looking into a cache of classified documents that Trump had stored at his Mar-a-Lago residence after leaving the White House.

The FBI carted away some 11,000 papers after serving a search warrant on Mar-a-Lago in August, and Trump could face obstruction of justice charges after spending months resisting efforts to recover the trove.

"No one has told me I'm being indicted, and I shouldn't be because I've done NOTHING wrong," Trump posted on his Truth Social network Wednesday, responding to media reports.

On Monday, US media also reported that Trump's lawyers John Rowley, James Trusty and Lindsey Halligan met with Justice Department attorneys -- they were seen by reporters arriving at the DoJ building in Washington, but did not make any comment.

The Washington Post reported at the time that Trump's lawyers had come to make their case that their client should not face any charges.