Donald Trump on Wednesday called for the prosecution of billionaire philanthropist George Soros, who has become a target of ultra-conservatives and conspiracy theorists, and his son for allegedly supporting violent protests across the country.

They "should be prosecuted under the RICO Act for their support of violent protests, and much more, throughout the United States of America," he wrote on his Truth Social network, referring to a federal law on criminal organizations.

George Soros, 95, and "his group of psychopaths have caused enormous damage to our country!" he added, without giving further details.

The Open Society Foundations (OSF), founded by George Soros, condemned Donald Trump's "outrageous and false" accusations in a statement sent to AFP.

The organization "does not support or fund violent protests. Our mission is to advance human rights, justice, and democracy here and around the world," a spokesperson said.

Hated by ultra-conservatives and a regular target of attacks with anti-Semitic overtones, the Hungarian-born billionaire has been accused by his detractors of having worked to overthrow governments and orchestrated a migration crisis in Europe.

The reason: the billions he has donated through his organization to support economic and justice reforms, minority and refugee rights, and freedom of expression.

During the June protests against Donald Trump's repressive immigration policies in Los Angeles, conservative social media accounts claimed, without evidence, that the rallies were fueled by nonprofit organizations backed by George Soros.

AFP journalists then demonstrated that photos circulating online and supposedly showing that bricks had been placed by these groups in strategic locations so that they could be thrown at the police had in fact been taken elsewhere.

One of George Soros's sons, Alexander, who took over the organization, had said he wanted to be more involved in the United States than his father, supporting programs encouraging Latino and African-American voters to vote and calling on Democratic elected officials to communicate better.

In January, former Democratic President Joe Biden awarded George Soros the prestigious Presidential Medal of Freedom.