A Swiss entertainer who made the world laugh is now under the microscope over his connections with Adolf Hitler and the Nazi’s.

The Neues Museum Biel is researching links between the performer, who was considered to be the greatest musical clown of his time, and the Nazi Germany dictator. 

Grock - whose real name was Adrien Wettach - became known as the "king of clowns" and his success once rivalled that of Charlie Chaplin. 

The museum in Biel has now taken possession of around 1,000 items from Grock's collection. Wettach’s 74-year-old great-nephew Raymond Naef donated items including sound recordings from shows, letters, photographs and musical scores.

Grock's stage costumes and musical instruments were also donated by Switzerland's Knie family circus dynasty via Naef.

Museum bosses said they were exploring the showman’s life off-stage before putting on any exhibition about him. 

Speaking to AFP, director Bernadette Walter said: “It's the museum's responsibility. It's absolutely necessary.”

Walter went on to say: “Grock says in his autobiography that Hitler came to his dressing room, and that Hitler saw his shows 13 times.” However, the museum has not yet verified the claim.

Grock

Portrait of professional clown Grock, born Charles Adrien Wettach (Photo: Getty)

During his lifetime, Wettach published several autobiographies whilst his great-nephew Naef wrote a book and curated a 2002 exhibition about Grock.

It also emerged that the museum tried to buy, for research purposes, a greetings telegram that Wettach sent to Hitler in 1942.

Walter explained: “We know that he met Hitler and (Joseph) Goebbels," the Nazi propaganda chief. However, whether he had any political allegiances remains a mystery.

It was also made clear that the museum did not consider turning down his archive.

Wettach performed in Germany before the Nazis came to power in 1933 but he always said he was apolitical and his autobiography mentions having doing shows in Britain, France and the United States.

The performer was born in 1880 and grew up in the Bernese Jura mountains above the city of Biel in northern Switzerland.

He chose the stage name Grock in the early 1900s, when he replaced Brock in Brick and Brock, a famous duo of the time.

Wettach passed away aged 79 in 1959.