Marilyn Monroe: Seven greatest quotes from the Hollywood icon

A letter suggesting Marilyn Monroe had an affair with US politician Robert Kennedy is among 1,200 items belonging to the Hollywood actor going under the hammer.

The letter, written to Monroe from Jean Kennedy Smith, the younger sister of Robert and John F Kennedy, appears to show the two were secretly an "item".

"Understand that you and Bobby are the new item!" writes Kennedy Smith. "We all think you should come with him when he comes back East!"

After more than half a century of unproven rumours, the document is "the most convincing evidence yet" the two were romantically involved, says the Daily Telegraph.

Much of the speculation linking Monroe and the Kennedys has centred on her alleged relationship with John when he was president. Robert Kennedy was married and already had eight children at the time of the letter.

The letter was found by relatives of acting coach Lee Strasberg, who became a father figure to Monroe, six years ago, when they were cleaning out suitcases and cupboards.

It will be auctioned in November in Los Angeles, along with lots including one of Monroe's costumes from the film Some Like It Hot and the negligee she wore in Niagara, together with a letter to her therapist complaining about her insomnia.

Several of the pieces were in Beijing for a private viewing this week. 

Born Norma Jeane Mortenson, Monroe became one of the most bankable Hollywood stars and most popular sex symbols of the 1950s and is still a cultural icon today. But by the time of her death, she had suffered from mental illness and substance abuse for several years.

She was found dead in her Los Angeles home on 5 August 1962, at the age of 36. An empty bottle of prescription medicine was discovered in the room and her death was put down to "probable suicide" caused by a "self-administered overdose of sedative drugs".

As well as her many hit films, Monroe is famous for a number of memorable quotes. Click on the gallery above to read seven of her best.