Leona 'will sing live on X Factor'

X Factor winner Leona Lewis has said she'll be performing on the show this series and will definitely sing live.

Leona won the third series of the talent show back in 2006 and releases her new single Happy on 9 November.

See also: Leona Lewis 'punched' at signing

The 24-year-old told Newsbeat: "I have to sing live when I go on there, that's what it's about - singing live.

"I won the show singing live every single week and you can't go back on and mime. Everyone sings live."

Her performance will follow that of fellow X Factor winner Alexandra Burke, who appeared on the show last weekend with a troupe of backing dancers.

'Great performance'

Some reports have speculated that she mimed part of her track but Leona didn't want to pass judgement.

"I know she was dancing a lot. I don't know if she was miming or not but I think it was a really great performance," she said.

Pop legend Robbie Williams made his comeback on the same show with a rendition of his new single Bodies.

The pair are going head to head in this week's charts, but figures suggest Alexandra's Bad Girls is outselling Robbie.

Bad Girls is the first single from Alexandra's debut album Overcome and it looks set to be the best-selling single of 2009.

This year's X Factor, which runs on both Saturday and Sunday nights, will host a series of performances from the likes of Whitney Houston and judge Cheryl Cole.