An object that appeared to be an explosive device has been found in a mailbox near the New York state home of philanthropist George Soros, the FBI and local police said.

Bedford police responded to the address in the town of Katonah on Monday afternoon after an employee of the residence opened the package.

The person placed the package in a wooded area and called police, who alerted the FBI and the Bureau of Alcohol, Firearms and Explosives.

Officers said the FBI’s terrorism task force is investigating.

The FBI’s New York field office said on Twitter that it was “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”.

Neither local nor federal authorities would say whether the object was capable of exploding.

Mr Soros, a billionaire who made his fortune in hedge funds, has donated heavily to liberal causes and is vilified on the right.

He is also the subject of many unfounded conspiracy theories. Recently, conservative critics have, without evidence, accused him of secretly financing a caravan of Central American migrants to make their way north towards Mexico and the US.

Others have falsely accused him of being a Nazi collaborator during the Second World War, when he was a child in Hungary.

Right-wing activists frequently post the addresses of homes he owns in Westchester County, north of New York City, on social media.