Secret love letters written by JFK to Swedish mistress expected to sell for £75,000 at auction

Affair: John F Kennedy sent the messages to his Swedish lover, Gunilla von Post

Secret love letters written by JFK to Swedish mistress expected to sell for £75,000 at auction . His affairs, from Marilyn Monroe to the reputed girlfriend of a Mafia boss, have been well documented.

But now never-before-seen love letters from John F Kennedy to a Swedish lover 15 years his junior are being put up for auction.

The secret messages, expected to fetch more than £75,000, were written to 21-year-old socialite Gunilla von Post when the future President was an ambitious U.S. senator in the 1950s.

Their friendship began a month before his marriage to Jacqueline Bouvier and continued afterwards, with Kennedy telling Miss von Post that he wanted to divorce his wife to be with her instead.

The pair shared a week-long tryst at a Swedish castle before Kennedy ended the affair and their two-year correspondence.

Miss von Post, now 78, revealed their affair in a 1997 book in which she claimed Kennedy talked with his father about divorce and arranging for her to move to New York and work as a model.

Secret: Eleven handwritten letters and three telegrams between JFK and his Swedish mistress Gunilla von Post are expected to sell for £75,000 at auction

But the 11 handwritten letters and three telegrams sent by Kennedy have remained private until now.

The pair first met in the south of France in the summer of 1953. After spending a night dancing, they parted with a kiss but Kennedy was so smitten that he later tracked down Miss von Post's address and began writing.

In the first letter dated September 1954, six months after his marriage, Kennedy says he expects to return to France and asks if she will be there. Three months later, Kennedy sent a second letter in which he expresses his longing to be with Miss von Post.

Saying that he is to visit Europe, he writes: 'I thought I might get a boat and sail around the Mediterranean for two weeks with you as crew. What do you think?'

Ambitious: JFK began the affair with Miss von Post before he married Jacqueline Bouvier and it carried on until 1955

Affair: The U.S. president was 15 years older than Miss von Post and was well known for a string of affairs, including one with Marilyn Monroe

But before the assignation could take place Kennedy sent a telegram cancelling it after suffering a crippling back injury that required extensive surgery.

In a November 1954 letter written from his hospital bed, he asks if she would visit the U.S.

The affair was finally consummated in August 1955 when the couple met at a castle in her native Sweden. Miss von Post said: 'I borrowed him for a week, a beautiful week that no one can take away from me.'

But months later the affair was over with Kennedy sending a last, handwritten note saying: 'I just got word today - that my wife and sister are coming here' and describing his emotions as 'complicated'.

Mistress: JFK had a number of affairs, including one with Hollywood star Marilyn Monroe, right, before he was assassinated in 1963

In July 1956 Miss von Post married Anders Ekman.

In her book, she revealed that she and Kennedy met for a final time at the 'April in Paris Ball' at the Waldorf-Astoria Hotel in New York in

She said they had a fleeting embrace, with Kennedy telling her: 'It's marvellous to se you' before parting.

The selection of letters are being sold by Chicago-based Legendaryauctions.com. 1958. ( dailymail.co.uk )