Cowell appeared on Pop Idol and American Idol before X Factor

The music mogul settled the case out of court in a deal which made Mr Fuller a joint partner in the X Factor show.

Mr Fuller had claimed Mr Cowell's ITV talent show X Factor copied his successful Pop Idol format, in a case taken to London's High Court.

As part of the settlement, Mr Cowell agreed to appear in at least five more series of American Idol.

Contract extended

Mr Fuller, creator of Pop Idol and American Idol, took action against X Factor producer FremantleMedia, Mr Cowell and his firms Simco and Syco.

He claimed X Factor copied the format of Pop Idol, which made a chart star out of singer Will Young.

Mr Fuller's firm 19 Entertainment also sued for breach of contract, alleging that members of X Factor's production team previously worked on Pop Idol and signed contracts preventing them working on rival shows.

Simon Fuller was the man behind the Spice Girls and S Club 7

While details of the out-of-court settlement remained confidential, 19 Entertainment will receive "a minority interest in certain intellectual property and programming related to the X Factor television programme".

US broadcaster Fox announced on Tuesday that it had agreed to retain Mr Cowell as a judge on American Idol - the US version of Pop Idol.

His contract had been due to expire at the end of the next series of American Idol, the most popular show on US television, which starts in January.

Mr Fuller said: "Simon Cowell has been a key component in the incredible success of American Idol and I am delighted to have reached an agreement that will see this relationship continue and grow over future years."

He said he and Mr Cowell were "capable of great things" when they were "focused and working closely together".