Donald Trump has been indicted following a years-long investigation by Manhattan prosecutors that has led to the first criminal charges against a former US president in the country’s history, according to his lawyers.

“President Trump has been indicted. He did not commit any crime. We will vigorously fight this political prosecution in court,” his lawyers Susan Necheles and Joseph Tacopina said in a statement.

The case against Trump, who is running as a Republican candidate for president in 2024, comes after a grand jury in New York heard evidence from witnesses including Michael Cohen, the former president’s one-time lawyer. Cohen has claimed he was ordered in 2016 to pay $130,000 to porn actor Stormy Daniels to cover up an alleged affair.

The exact nature of the charges was not immediately known. The New York Times first reported the indictment, which it said would be filed under seal.

“This is political persecution and election interference at the highest level in history,” Trump said in a statement after his lawyers were informed of the charges. “The Democrats have lied, cheated and stolen in their obsession with trying to ‘get Trump’, but now they’ve done the unthinkable — indicting a completely innocent person.”

Whether the payments to Daniels, whose real name is Stephanie Clifford, violated campaign finance and accounting laws has been the subject of a four-year investigation by the Democratic-led Manhattan district attorney’s office. Cohen was sentenced in 2018 to three years in prison after pleading guilty to charges including campaign finance violations linked to the payment.

The charges come after two weeks of intense speculation about the investigation by the Manhattan district attorney, Alvin Bragg, which started when Trump announced that he expected to be arrested last week. Media reports earlier this week indicated the grand jury hearing evidence was prepared to take an extended break from its work, prompting observers to ask whether the investigation had run aground.

Trump is expected to be arrested and processed like anyone else facing criminal charges, including being fingerprinted and photographed before entering a plea and being released on bail.

The indictment is all but certain to trigger a fierce backlash from Trump’s supporters in Washington and across the country. Jim Jordan, the Republican chair of the House judiciary committee and a staunch supporter of the former president, issued a one-word press release following the reports: “Outrageous.”

Trump himself had called for his supporters to protest and “take our nation back” in the event that he was indicted and arrested.

Earlier this month, Trump told reporters at the CPAC conference of conservative activists that he would stay in the race for the White House if he were indicted.

“I wouldn’t even think about leaving,” Trump said at the time. “Probably it will enhance my numbers.”

A Quinnipiac University poll out on Wednesday showed 57 per cent of Americans think Trump should be disqualified from running for president if he faces criminal charges. Fifty-five per cent said the accusations being investigated by the Manhattan district attorney were “serious”.

But Trump nevertheless remains the favourite among the Republican grassroots who will select the party’s nominee for president in 2024.

Trump was the first Republican to declare his candidacy, shortly after last November’s midterm elections, and so far only former UN ambassador Nikki Haley and anti-ESG investor Vivek Ramaswamy have formally launched campaigns to challenge him.

The Manhattan DA’s office secured a criminal conviction against the former president’s businesses last year over a 13-year tax fraud scheme carried out by senior executives at the Trump Organization.

Trump is also facing a civil case brought by the New York attorney-general’s office, and is under investigation in Georgia over his alleged attempts to overturn the 2020 presidential election.

A special counsel at the Department of Justice is considering whether to charge Trump over his alleged role in inciting riots on Capitol Hill in January 2021.

The DA’s office did not immediately comment.