(AFP) - Donald Trump was indicted Monday on charges of racketeering and a string of election crimes after a sprawling, two-year probe into his efforts to overturn his 2020 defeat to Joe Biden in the US state of Georgia.

The case -- relying on laws typically used to bring down mobsters -- is the fourth targeting the 77-year-old Republican this year and could lead to a watershed moment, the first televised trial of a former president in US history.

Prosecutors in Atlanta charged Trump with 13 felony counts -- compounding the legal threats he is facing in multiple jurisdictions as a firestorm of investigations imperils his bid for a second White House term.

Eighteen co-defendants were indicted in the probe, including Trump's former personal lawyer Rudy Giuliani, who pressured local legislators over the result after the election, and Trump's White House chief of staff, Mark Meadows.

With Trump already due to go on trial in New York, south Florida and Washington, the latest charges herald the unprecedented scenario of the 2024 presidential election being litigated as much from the courtroom as the ballot box.

"Rather than abide by Georgia's legal process for election challenges, the defendants engaged in a criminal racketeering enterprise to overturn Georgia's presidential election result," Fulton County prosecutor Fani Willis told reporters.

Willis said Trump and his co-defendants had until noon on August 25 to "voluntarily surrender" to authorities, adding that she would like to go to trial within six months.

"So, the Witch Hunt continues!" Trump posted on his Truth Social platform.

"Sounds Rigged to me! Why didn't they Indict 2.5 years ago? Because they wanted to do it right in the middle of my political campaign. Witch Hunt!"

His lawyers' statement took issue with the "leak of a presumed and premature indictment before the witnesses had testified or the grand jurors had deliberated", in what they say has been a "flawed and unconstitutional" process.

In response to similar allegations by the Trump campaign, Willis said: "I make decisions in this office based on the facts and the law. The law is completely nonpartisan."

The twice-impeached Trump was charged with violating Georgia's Racketeer Influenced and Corrupt Organizations (RICO) Act, as well as six conspiracy counts over alleged efforts to commit forgery, impersonate a public official and submit false statements and documents.

He is also accused of lying in statements and filing fake documents, as well as soliciting public officials to break their oaths.

- Most serious threat -

Georgia, which Biden won by fewer than 12,000 votes, presents perhaps the most serious threat to Trump's liberty as he leads the field comfortably for his party's nomination to bid for reelection.

Even if he is returned to the Oval Office, he would have none of the powers that presidents arguably enjoy in the federal system to pardon themselves or have prosecutors drop cases.

The harsh penalties associated with RICO cases can be an incentive for co-defendants to seek cooperation deals, and the statutes are usually used to target organized crime.

Thirty unindicted co-conspirators were mentioned in the indictment.

Under federal law, anyone who can be connected to a criminal "enterprise" through which offenses were committed can be convicted under RICO. The broader Georgia law doesn't even require the existence of the enterprise.

Atlanta-area authorities launched the probe after Trump called Georgia officials weeks before he was due to leave the White House, pressuring them to "find" the 11,780 votes that would reverse Biden's victory in the Peach State.

Meadows, who is accused of trying to get a public official to violate his oath, was on the call.

- Secret report -

Willis empaneled a special grand jury that heard from around 75 witnesses before recommending a raft of felony counts in a secret report in February.

She alleges that Trump's team worked with local Republicans on a scheme to replace legitimate slates of "electors" -- the officials who certify a state's results and send them to the US Congress -- with fake pro-Trump stand-ins.

The indictment lists a litany of telephone calls made by Trump, Giuliani and others to various state officials for the purpose of unlawfully appointing fake electors to swing the Electoral College in Trump's favor.

Giuliani faces 13 felony counts, including over accusations of harassment of two Fulton County poll workers.

Other Trump allies were charged over the accessing of sensitive data from an election office in a rural county south of Atlanta one day after the 2021 Capitol riot.

Trump is already facing dozens of felony charges after being federally indicted over the alleged plot to subvert the election, and further prosecutions over his alleged mishandling of classified documents and keeping allegedly fraudulent business records.

Authorities in Atlanta installed security barricades outside the downtown courthouse in anticipation of a potential influx of Trump supporters and counter-protesters in the latest case.

Lawmakers investigating Trump's efforts to cling to power heard evidence in a series of congressional hearings last summer that would challenge his potential defense that he genuinely believed he had been cheated of the election.

Agence France-Presse