A prosecutor who resigned from the February investigation into Donald Trump's business practices said the former president "committed numerous wrongdoing", notably financial fraud, according to his resignation letter published by the New York Times on Wednesday.

Attorney General Mark Pomerantz - who headed the investigation conducted by the New York authorities into Trump's financial affairs - had resigned on February 23, and said - in his letter - that this came against the backdrop of Alvin Bragg, the Manhattan District Attorney's decision not to proceed with the prosecution of the Republican billionaire.

He wrote in the letter, the full text of which was published by the American newspaper, that the decision "contradicts the public interest."

"The investigation team into Mr. Trump has no doubts that he committed wrongdoing," Pomerantz added.

The investigation was looking at whether Trump fraudulently inflated the value of several assets to secure loans, then undervalued them to cut taxes.

The investigation was launched by Prague's predecessor, Prosecutor Cyrus Vance, before he moved to Prague as he took over as Manhattan's attorney general in January.

When Dan and Pomerantz resigned last February, a Prague spokesman said the investigation was "ongoing".

The New York Times reported that he told his aides that the case could move forward if new evidence emerged, or if someone close to Trump decided to turn against the former president.

However, Pomerantz wrote, "It is unlikely that there will be events that will change the nature of the case... There will always be additional facts to be pursued."

But the decision not to prosecute "will cast a shadow over any future prospects of Trump being prosecuted for the criminal conduct that we have investigated."

Trump, the 75-year-old Republican, has not been charged, and has said more than once that the case is a "political manhunt" launched by a Democratic attorney general.

In July, 15 criminal and tax evasion charges were brought against the Trump Organization and its chief financial officer, Alan Wesselberg.

Trump has not yet revealed whether he intends to fight the Republican Party's battle to choose his candidate for the presidential elections again, but the numerous judicial investigations threaten to complicate any effort to win the race for the White House in 2024.