A British spy probe into Charlie Chaplin was unable to find any evidence of the silent film star's birthplace, while his real name was shrouded in mystery, newly released documents reveal.

MI5 agents were asked in 1952 to investigate Chaplin's background by the United States, which believed the actor was a communist sympathiser whose real name was Israel Thornstein.

Chaplin, one of Hollywood's first and greatest stars famed for his 'Little Tramp' character, believed he was born in south London on April 16, 1889.

But an exhaustive search by MI5 found no record of his birth anywhere, nor anything to suggest he was any kind of security risk, declassified files from MI5 reveal.

"It's very unusual, particularly after investigation by MI5, for the date and place of birth for such a well-known celebrity as Charlie Chaplin to remain so mysterious," said Professor Christopher Andrew, the official historian of MI5.

The file shows no one called Charles or Israel was born on April 16, 1889 in London, and further inquiries into suggestions Chaplin had been born in France near Fontainebleau also proved fruitless.

"We can find no evidence that Chaplin's name is or ever has been Israel Thornstein, nor can we find any evidence of the existence of such a person," MI5 said in a letter to the US embassy in London.

"We have, however, been unable to discover any other name by which he has been known."

Professor Andrew said new evidence which emerged last year suggested Chaplin was born in a caravan belonging to a woman known as "the Gypsy Queen" in central England and his mother was a member of what is now referred to as "the travelling community".

The information was in a letter, found in a locked drawer, which had been sent to Chaplin a few years before his death in 1977 by a man called Jack Hill, who said the caravan's owner was his aunt.

"Though there's no proof that Jack Hill's information is correct, Chaplin obviously treated it seriously; otherwise, as his oldest surviving son has commented, Chaplin would not have preserved it so carefully," Professor Andrew said.

Controversial career

During his long career, Chaplin courted controversy with overtly political films such as The Great Dictator, a parady of German Nazi leader Adolf Hitler, and A King in New York, a satire on the anti-communist Cold War fears gripping America.

From the 1920s, US authorities suspected him of being a communist supporter, a claim he always denied, and he was refused a re-entry permit when he left the US in 1953 and went to live in Switzerland.

The MI5 file - which includes press cuttings, letters to and from the US embassy and a telegram to Chaplin from a Soviet agent - shows the British agency also rejected the US claims and concluded in 1958 he posed no risk.

"It may be that Chaplin is a communist sympathiser, but on the information before us he would appear to be no more than a 'progressive' or radical," an MI5 officer wrote.

Among other declassified documents released were details of MI5 investigations into three Nobel prize-winning chemists, including Irene Curie and her husband, who were communist sympathisers.

Another file also details the actions of Folkert Van Koutrik, a Dutch double agent who worked for German intelligence during World War II.

Reuters