Republican presidential candidate Donald Trump accused Democratic rival President Joe Biden of running a "Gestapo administration" in a private address to donors in which he also attacked prosecutors involved in his criminal indictments, according to a recording heard by U.S. media outlets.

Trump, whose own rhetoric has drawn accusations of fascist tendencies from civil rights groups and other critics, made the comparison with the Nazi police in Germany's World War Two regime at a donor retreat Saturday night at his Mar-a-Lago resort in Palm Beach, Florida.

The comments came after Trump reprised his complaint that the multiple indictments against him were politically motivated. He had just concluded 11 days of a New York hush money trial in which he is charged with falsifying business records to cover up a $130,000 payment made to a porn star.

"These people are running a Gestapo administration," Trump said, according to an audio recording heard by the New York Times and the Washington Post. "And it's the only thing they have. And it's the only way they're going to win, in their opinion, and it's actually killing them. But it doesn't bother me."

The Trump campaign did not respond to a request for comment on the reported remarks.

In a statement, White House spokesman Andrew Bates sought to contrast Biden's conduct in office with Trump's latest remark, accusing the former president of echoing fascist rhetoric, "lunching with neo-Nazis and fanning debunked conspiracy theories that have cost brave police officers their lives."

"President Biden is bringing the American people together around our shared democratic values and the rule of law - an approach that has delivered the biggest violent crime reduction in 50 years," said Bates.

Trump, who held office from 2017 to 2021, faces an array of legal troubles in criminal and civil cases while he seeks to regain the presidency in the Nov. 5 election. He denies wrongdoing in all the cases.

Trump has made a series of inflammatory and racist statements on the campaign trail, using violent imagery to lambaste immigrants and opponents. He has warned of possible violence if he doesn't win the 2024 election and has compared immigrants to animals.

In November, Biden attacked Trump for using the word "vermin" to refer to his political enemies, saying it echoed the language of Nazi Germany. Also last year, Trump said immigrants who entered the country illegally were "poisoning the blood of our country."

Some historians say such comments mirror that of autocrats who have sought to dehumanize their foes. The Trump campaign has previously rejected comparisons to Nazis, Adolf Hitler and Italy's Benito Mussolini.

The Jewish Council for Public Affairs denounced the Nazi comparison on Sunday.

"It's always wrong, offensive, and despicable to make comparisons like this — even more so when taken alongside the former president's long history of normalizing antisemitism," said Amy Spitalnick, chief executive of the public policy group.

It was "especially heinous to use Nazi comparisons in the service of a bigoted, authoritarian agenda," she said.

On Saturday night, Trump again took swipes at the federal and Georgia prosecutors working on cases against him, according to the media reports.

Trump, a former New York businessman and reality television host, described Mexican immigrants as rapists and drug smugglers as he declared his candidacy for the Republican nomination in the 2016 election. He drew widespread criticism after a violent 2017 rally in Charlottesville, Virginia, for equating white supremacists with counter-protesters and saying "both sides" were to blame.

Biden has said the events in Charlottesville, where one woman was killed, motivated him to run for president against Trump in 2020.