Simon Cowell has announced he is quitting the top-rated Fox TV show in May to launch his own singing contest next year. He also confirmed he plans to bring a U.S. version of his British show The X Factor to Fox in the fall of 2011.

Cowell said he had been offered "a lot of money" to renew his contract with American Idol, whose average audiences have slipped from 30.8 million in 2006 to 26.3 million in 2009.

"But I felt like doing something different. I want to leave 'Idol' this year bigger and better than before," he said.

"We did talk about me staying on both shows, but when we looked at the practicalities of that, it was impossible."