Simon Cowell has reportedly offered Katy Perry and boyfriend John Mayer $20m to join the X Factor USA.

The couple, who are believed to have dated on-and-off since last July, are being approached to replace departed judges Britney Spears and LA Reid in the hope that they will have ”unmissable” on-air spats.

“Simon sees it as a brilliant pairing,” Now quotes a source as saying. ”Katy’s sassy, honest and a huge star, while John’s more reserved.”

“Having them as rivals would be genius - if they had on-air best-ups, it’d be unmissable.”

Perry appeared as a guest judge on the UK X Factor in 2010, but has since turned down offers to join the show full-time.

“People have reached out to me about the possibility of being involed [in reality shows] and I think that it’s not right for me right now,” she said last year.

“I have ideas for two or three big, creative things and I want to be able to fulfill those ideas. And it’s a real commitment to be on one of those shows.”

The third season of X Factor is set to premiere this fall on FOX.