Wendi Deng, the former wife of Rupert Murdoch, wrote a "lovelorn" note about Tony Blair in which she praised his "good body and really really good legs (and) butt".
Ms Deng (45) is said to have become infatuated with the former prime minister while she was still married to the 82-year-old media mogul.
In the note, Chinese-born Ms Deng wrote in broken English: "Oh, s***, oh, s***. Whatever why I'm so so missing Tony. Because he is so so charming and his clothes are so good.
"He has such good body and he has really really good legs Butt ... And he is slim tall and good skin. Pierce blue eyes which I love. Love his eyes. Also I love his power on the stage ... and what else and what else and what else... (all sic)."
The contents of the sensational, undated note are detailed in 'Vanity Fair' magazine, which described it as "a steamy, lovelorn missive".
Mr Blair (60) has denied all allegations of an affair with Ms Deng, whose friends say the pair were never more than friends.
Mr Murdoch's discovery of his wife's crush on Mr Blair was said to be the "final straw" that prompted him to file for divorce after 14 years of marriage. The News Corp executive chairman felt "betrayed" as he considered Mr Blair to be a close ally.
According to 'Vanity Fair', a besotted Ms Deng invited Mr Blair to spend a weekend at the Murdoch family ranch in Carmel, California, in October 2012 – omitting to tell him that her husband would not be there.
"Mr Blair was reluctant at first. They were all mutual friends, there was no reason Mr Murdoch wouldn't have welcomed Mr Blair into his home," a Murdoch staff member told the magazine.
"But one day Mr Blair arrived and Mrs Murdoch was sort of being very flirtatious. She was charming him.
"He asked staff, 'when is Mr Murdoch going to arrive?' And when he was told, 'tomorrow night'. Mr Blair rolled his eyes and gave a panicked look."
Ms Deng had allegedly told her husband that she was spending a "girls' weekend" at the ranch in Carmel. That weekend, Mr Murdoch's 103-year-old mother, Dame Elisabeth, had been released from hospital and was thought to have only days to live, so family had gathered at her bedside.
The Australian media mogul began to hear rumours about his wife in 2012 and is said to have interviewed staff members at his various homes to ask them what they had seen.
According to the magazine, he learnt Mr Blair had visited Ms Deng at the ranch on more than one occasion. He allegedly also spent the weekend of April 27 last year with Ms Deng at the property.
Other sources were quoted as placing Mr Blair and Ms Deng at the Carlyle hotel in New York, on a private yacht and at Mr Murdoch's home in London.
Mr Blair, who has been married to Cherie for nearly 34 years, declined to comment on the article but has said in the past that allegations of an affair are untrue. He was for many years a family friend of the Murdochs and is godfather to the eldest of their two daughters, Grace, now 12.
A joint statement from Ms Deng and Mr Murdoch to 'Vanity Fair' said: "Given the complicated dynamics of our family, we made the decision not to engage in public allegations or respond to negative claims." (© Daily Telegraph, London)