London: Rihanna has turned down Simon Cowell's offer to judge the 'X Factor' show.
A source said that the 'Diamonds' singer was Cowell's ultimate choice and she was right at the top of ITV's hitlist, the Daily Star reported.
The source asserted that having the Barbadian singer on the panel next to Cheryl Cole and Cowell would have been a ratings-winning dream team but everyone had accepted that it was not going to happen now.
The 54-year-old TV producer said that the singer would like to do it but he doubted that she might take some time.
Cowell added that Louis Walsh will make a comeback after seeing off Tinie Tempah.