Pete Waterman thinks Girls Aloud are too full of "bitterness" to ever reform.

The music mogul helped form the popular group - comprised of Cheryl Tweedy, Sarah Harding, Kimberley Walsh, Nadine Coyle and Nicola Roberts - when he was a judge on 'Popstars: The Rivals' in 2002 but insists their toxic relationship 15 years on will stop them from ever reviving the chart topping band.

He said: "No, there's quite a bit of bitterness. I think they fell out quite badly, and I don't think they talk to each other."

Sarah is currently starring in 'Celebrity Big Brother' but the blonde has regularly broken down in tears inside the infamous house and Pete said she is barely recognisable from the fresh-faced pop star he once knew.

He told The Sun newspaper: "She's nothing like how I knew her. She was one of the sweetest kids. It's a long time ago - 15 years. She certainly wouldn't have done this 15 years ago."

Sarah recently hinted she'd had a falling out with Cheryl and, although she refused to divulge why their friendship had fizzled out - despite once being like "sisters" - she's confident things will be fine between them eventually.

Asked whether they'd had a falling out, Sarah - who recently admitted to having a "mini-meltdown" every four weeks - said: "Everyone asks that but we're so busy with our own stuff. It's not for me to say.

"Honestly, it's not for me to say. I don't like talking about the other girls if it's a personal thing. I mean, we were like sisters, so of course it would never be plain sailing the whole time. Being around girls all the time is difficult, you know? Nothing lasts forever. We went through so much, even if had fallen out, I'm sure it wouldn't be a major deal in the future."