Diana Mosley (centre) at a Nazi rally

She died on Monday in Paris, according to a death notice published in The Times newspaper.

The notice, in the deaths column, read "MOSLEY - On 11th August 2003, Diana widow of Sir Oswald Mosley Bt peacefully in Paris, aged 93."

A spokesman for the estate of her sister Deborah, the Duchess of Devonshire, said: "We can confirm that she died peacefully but we cannot say any more than that."

She is to be buried in Oxfordshire next week.

Diana Mosley was born into the aristocratic Mitford family on 17 June, 1910.

Winston Churchill, Evelyn Waugh and John Betjeman were among her circle of friends.

She was 18 when she married one of the Guinness heirs, Bryan Guinness, but three years later she met Mosley - Westminster's youngest MP - and left her husband to become his mistress.

She married the founder of the British Union of Fascists in Joseph Goebbels's drawing room in 1936. Adolf Hitler was a guest.

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The Nazi dictator described her as an "angel" and the Mosley couple made frequent trips to Germany, attending the Nuremberg rallies.

Lady Mosley remembered him as having "extraordinary mesmeric eyes".

"Also he had so much to say - I mean, he was so interesting."

By 1940, their links to Hitler caused them to be viewed as outcasts.

Sir Oswald Mosley was arrested and she joined him behind bars at Holloway Prison in London, where they remained until being released in 1943 on the grounds of his ill-health.

MI5 documents released in November last year revealed that the security services regarded Diana Mosley as the greater threat.

One report read: "Diana Mosley, wife of Sir Oswald Mosley, is reported on the best authority, that of her family and intimate circle, to be a public danger at the present time.

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"Is said to be far cleverer and more dangerous than her husband and will stick at nothing to achieve her ambitions. She is wildly ambitious."

Her sister, Unity Mitford, was also an admirer of Hitler and was described as "more Nazi than the Nazis".

Unity shot herself when World War II began, causing herself severe brain damage, and she died in 1948 from her injuries.

The Mosleys moved to France in the 1950s.

Sir Oswald died in 1980 and as a widow, Lady Mosley remained in Paris to continue her husband's work.