MIAMI (AP) — Donald Trump has been indicted on felony charges of mishandling classified documents at his Florida estate, a remarkable development that makes him the first former president in US history to face criminal charges by the federal government that he once oversaw.

The Justice Department was expected to make public an indictment ahead of a historic court appearance next week in the midst of a 2024 presidential campaign punctuated by criminal prosecutions in multiple states. Trump's indictment carries unmistakably grave legal consequences, including the possibility of prison if he's convicted.

But it also has enormous political implications, potentially upending a Republican presidential primary that Trump had been dominating and testing anew the willingness of GOP voters and party leaders to stick with a now twice-indicted candidate who could face still more charges. And it sets the stage for a sensational trial centred on claims that a man once entrusted to safeguard the nation's most closely-guarded secrets willfully, and illegally, hoarded sensitive national security information after leaving office.

The Justice Department did not immediately confirm the indictment publicly. But two people familiar with the situation who were not authorised to discuss it publicly said that the indictment included seven criminal charges. One of those people said Trump's lawyers were contacted by prosecutors shortly before he announced Thursday on his Truth Social platform that he had been indicted.

Within minutes of his announcement, Trump began fundraising off it for his presidential campaign. He declared his innocence in a video and repeated his familiar refrain that the investigation is a “witch hunt.” He said he was due in court Tuesday afternoon in Miami, where a federal grand jury had been hearing testimony as recently as this week.

The case adds to deepening legal jeopardy for Trump, who has already been indicted in New York and faces additional investigations in Washington and Atlanta that also could lead to criminal charges. But among the various investigations he has faced, legal experts — as well as Trump's own aides — had long seen the Mar-a-Lago probe as the most perilous threat and the one most ripe for prosecution. Campaign aides had been bracing for the fallout since Trump’s attorneys were notified that he was the target of the investigation, assuming it was not a matter of if charges would be brought, but when.

Appearing Thursday night on CNN, Trump attorney James Trusty said the indictment includes charges of willful retention of national defense information — a crime under the Espionage Act, which regulates the handling of government secrets — obstruction, false statements and conspiracy.

The case is a milestone for a Justice Department that had investigated Trump for years — as president and private citizen — but had never before charged him with a crime. The most notable investigation was an earlier special counsel probe into ties between his 2016 campaign and Russia, but prosecutors in that probe cited Justice Department policy against indicting a sitting president. Once he left office, though, he lost that protection.

The inquiry took a major step forward last November when Attorney General Merrick Garland, a soft-spoken former federal judge who has long stated that no one person should be regarded as above the law, appointed Jack Smith, a war crimes prosecutor with an aggressive, hard-charging reputation to lead both the documents probe as well as a separate investigation into efforts to subvert the 2020 election.

The indictment arises from a monthslong investigation into whether Trump broke the law by holding onto hundreds of documents marked classified at his Palm Beach property, Mar-a-Lago, and whether Trump took steps to obstruct the government’s efforts to recover the records.