Eric Clapton enjoyed a romantic liaison with Britain's Princess Diana, a new book has claimed.

The 70-year-old guitarist enjoyed a flirtation with the late princess - who separated from husband Prince Charles in 1992 - after meeting regularly at his favourite restaurant, San Lorenzo in London's upmarket Knightsbridge.

Paul Scott wrote in his new book 'Motherless Child: The Definitive Biography of Eric Clapton': ''One who regularly caught his eye was another San Lorenzo devotee, Princess Diana. They had first been introduced backstage at a charity concert for Prince Charles' the Prince's Trust at Wembley Arena in June 1987. Clapton later cringed that he had rather presumptuously addressed her as 'Di'. For her part, the princess didn't bat an eyelid.

''According to a society friend of Clapton's, who was also on speaking terms with Diana, the attraction between them was 'absolutely obvious'.

'''There was a 'Carry On' film element to it,' says the friend. 'A lot of winking, and overtly steamy looks.

''A story went around that one time when she and Eric were both at San Lorenzo, Diana began sucking suggestively on a piece of ice as she gave him the eye. Everyone loved that.

''Did things ever go any further? 'Well,' says the friend, 'they were both free agents and Eric's always liked a challenge.' ''

The author went on to suggest the 'Wonderful Tonight' hitmaker and the princess were able to enjoy the ''utmost discretion'' of the eatery's owner.

However, it seems things didn't end well between the pair.

In an extract from the book obtained by the Daily Mail newspaper, the author added: ''Perhaps whatever there was between them soured, because a decade after her death, Clapton would describe Diana as a 'manipulative and sick person'.''