On Truth Social - the social media network he created - the former US president suggested that the indictment is linked to his handling of classified documents.

Mr Trump's lawyer, John Rowley, said the 76-year-old had been charged on seven counts. The specific charges against Trump are still unknown.

The Republican politician - who wants to run for president again in 2024 - said his legal team had been informed of the indictment by Joe Biden's administration.

Mr Trump said he is due to appear in court in Miami, Florida, on Tuesday.

He wrote: "I never thought it possible that such a thing could happen to a former President of the United States, who received far more votes than any sitting President in the History of our Country, and is currently leading, by far, all Candidates, both Democrat and Republican, in Polls of the 2024 Presidential Election. I AM AN INNOCENT MAN!"

In a further post, he added: "This is indeed a DARK DAY for the United States of America. We are a country in serious and rapid decline, but together we will Make America Great Again!"

Mr Trump later posted a four-minute video of himself discussing the allegations, which he described in the clip as a "hoax".

"We have such big problems - this shouldn't be one of them," he added.

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"I'm an innocent man. I did nothing wrong. I will fight this, just like we've been fighting for seven years.

"I'm an innocent man, we will prove it again. Seven years of proving it and here we go again. Very unfair - but that's the way it is."

House Republican conference chairwoman, Elise Stefanik, was among those to criticise the news of the indictment and accused government officials of an "endless illegal witch-hunt" against Mr Trump.

Texas Republican Troy Nehls wrote on Twitter: "We live in a Banana Republic," while Mr Trump's son Donald Trump Jr. shared a similar reaction, describing the US as a "third world Banana Republic".

But New York Democrat congressman Adriano Espaillat wrote on Twitter: "A friendly reminder… no one is above the law. Not even a former president."

The indictment comes after a months-long investigation by special counsel Jack Smith into whether Mr Trump broke the law by holding onto hundreds of documents marked classified at his Palm Beach property Mar-a-Lago.

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The investigation also looked into whether the former president took steps to obstruct the government's efforts to recover the records.

In August, the FBI carried out a raid on Mr Trump's Mar-a-Lago estate in August last year as part of an investigation into whether Mr Trump took the documents from the White House.

Officers seized 33 boxes containing more than 100 classified records during the search and found three confidential documents stashed in office drawers, a filing released last August revealed.

FBI and justice department officials had previously visited a storage room at the Florida estate in June, after issuing a subpoena for the missing records.

The indictment comes less than three months after Mr Trump was charged in New York with 34 felony counts of falsifying business records.

Those counts relate to an alleged "hush money" payment to adult film actress Stormy Daniels during the 2016 presidential election campaign.

It was allegedly made in exchange for Ms Daniels' silence about an alleged sexual encounter she said she had with Mr Trump a decade earlier.

Mr Trump has denied having sex with Ms Daniels and has called the indictment "political persecution".