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In an explosive biography by former BBC journalist Tom Bower, The Intimate Life of Simon Cowell, numerous quotes are given about Cowell's alleged infatuation with the pop star and have led to mass speculation that the pair engaged in an affair. These rumours coincide with the end of Minogue's four-year relationship with ex-footballer and model Kris Smith.
In the book, Cowell is quoted as saying "I had a crush on her. It was Dannii's hair, the sexy clothes and the t**s. I was like a schoolboy. She was foxy. She was a real man's girl. Very feminine."
The music mogul took to Twitter last night to comment on the allegations, saying: "Just seen the TV ad for the unauthorised book on me. Yikes!"
This is not the first time rumours have circulated about the pair being an item.
In 2008 -- just before Minogue met Smith -- a grainy photo of Cowell and Minogue in the back of a car appeared to show the pair holding hands, a claim which Minogue denied at the time.
The pair finished working together on the UK version of 'The X-Factor' in 2010 due to reported scheduling conflicts with Minogue's Australian judging commitments on TV show 'Australia's Got Talent'.
The book also claims Cowell had a string of high profile female pursuits, including fellow Aussie Natalie Imbruglia and also fellow British 'X-Factor' judge Cheryl Cole.Related Video: Was a bad Christmas present responsible for Dannii and Kris' split?