Cowell's televised talent competitions are among the commercial channel's biggest draws, generating millions of pounds in advertising income and helping it compete with rival BBC's increasingly aggressive reality TV drive.

According to Tom Bower, whose unauthorized biography of Cowell has been serialized this week in the Sun tabloid and hits the shelves on Friday, ITV bosses failed to respect Cowell and properly appreciate what he had done for the channel.

"He (Bower) admitted revelations in his book ... risked pushing to crisis point relations between the station and the man behind their most successful shows," the Sun reported.

The newspaper valued the multi-year partnership at 100 million pounds ($160 million).

But Max Clifford, Cowell's publicist, played down any rift.

"Simon and ITV have had a very close and hugely successful relationship for many years," he told Reuters, when asked about Bower's comments.

"Inevitably they don't agree on everything all the time, but the overall situation is as healthy, good and mutually beneficial as it's ever been."

ITV, which has signed up both shows until 2013, issued a statement in response to the reports.

"We're continuing to work closely with Simon and the production teams to ensure that the shows are the very best they possibly can be and we are looking forward to the remainder of the run and the exciting week of live shows."

Clifford said he did not think Cowell should have spoken to Bower, who was given hundreds of hours of access to the 52-year-old when writing "Revenge: The Intimate Life of Simon Cowell".

"EMBARRASSING, BUT FALLOUT LIMITED"

The Sun, Britain's best-selling daily, has splashed details of Cowell's private life across its pages for several days, causing embarrassment to the parties involved but also ensuring the impresario remains in the public eye at a time when Britain's Got Talent ratings are lower than expected.

Clifford said some of the stories, including an affair with a fellow TV judge, had undoubtedly knocked Cowell's image.

"Is it embarrassing? Yes," Clifford said. "Did he realize he made a mistake (in talking to Bower)? Yes. But in a month's time, how much damage will have been done? Providing Britain's Got Talent gets big ratings, then very little.

"It's more a question of personal embarrassment to Simon as a man than damage to his image and commercial success and standing in my view."

According to the Sun, one bone of contention between Cowell and ITV has been the choice of The X Factor judge Gary Barlow.

Earlier this week ITV confirmed the Take That singer would be returning to the hit series this year, despite Cowell's reservations about his performance in 2011.

Cowell, a major global celebrity thanks to his acerbic judging style, left the show last year in order to launch a U.S. version of "The X Factor".

He is already a familiar face in the United States thanks to his starring role on the panel of "American Idol", created by his one-time partner and now arch-rival Simon Fuller.

That personal rivalry is a major driving force behind Cowell's North American ambitions, according to a source familiar with the situation.

A second series of the U.S. X Factor has been commissioned, and Cowell will be hoping to improve on 2011 ratings which, while solid, were only about half those enjoyed by "Idol".

In a typically blunt admission, Cowell said in December that he had been a "little too cocky" when he brought the show to the United States but vowed the second season would be better.

Even in Britain Cowell's dominance is under threat, with the BBC's "Strictly Come Dancing" last year and new show "The Voice" this year putting a serious dent in audiences for The X Factor and Britain's Got Talent respectively.

(Reporting by Mike Collett-White, editing by Paul Casciato)

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