An explosive device was found in the mailbox of billionaire philanthropist George Soros, police have said.

The package was found at his New York home on Monday afternoon by one of Mr Soros’s employees, who alerted the authorities before taking it to a wooded area, according to media reports.

It did not explode on its own, with bomb squad technicians “proactively detonating” the package. The case is now under FBI investigation.

We are conducting an investigation at and around a residence in Bedford, NY. There is no threat to public safety, and we have no further comment at this time.

— FBI New York (@NewYorkFBI) October 23, 2018

Mr Soros, a Holocaust survivor born to a Hungarian Jewish family, entered the public eye as one of the world’s foremost currency speculators, before turning his attention to humanitarian and political causes over the last two decades.

The 88-year-old is a favourite target of the far-right and antisemitic conspiracy theorists, and was the subject of an aggressive political campaign by Hungarian Prime Minister Viktor Orbán, which was condemned as racist.

Earlier this month, Donald Trump repeated the conspiracy theories about Mr Soros when he tweeted that anti-Republican protestors were "paid for by Soros and others".

Mr Soros was not at his home, in Westchester County, New York, at the time of the incident.

A Bedford Police Department official told the New York Times: “An employee of the residence opened the package, revealing what appeared to be an explosive device.”