Cowell says fame damages children. Well, he did in 2004

It is the first rule of showbiz: never work with animals or children. But even an old pro such as Simon Cowell can get caught out. As the fourth series of Britain's Got Talent kicked off last night, with bookies tipping a 10-year-old schoolgirl as the favourite, it emerged that Cowell had previously admitted fame can do "serious damage" to young children.

His remarks, in a 2004 interview, three years before the ITV show hit our screens, sit uncomfortably with the fortune Cowell and his company, Syco, has made from the format.

Britain's Got Talent has catapulted dozens of children into the public eye and created celebrities out of the dancer George Sampson, 14, and mezzo-soprano Faryl Smith, 12. This January, a four-year-old boy from Peterborough, Kayim-Ali Jaffer, auditioned as a Michael Jackson impersonator. But in the 2004 interview Cowell said he felt even a 16-year-old was not old enough to cope.

Speaking to the US interviewer Terry Gross in her Fresh Air show, Cowell cited Jackson as a reason why children should not be entered into talent contests. "I have a problem with that. I even have a problem with people entering at 16. They're just not ready for it. Look at Michael Jackson – take somebody in at an early age and see what happens. You lose your growing-up period. This is what happens when you go into the music industry at such an early age.

"You say that to 11-year-olds and they're never going to listen to you because they want to be rich and famous. But when you deprive someone of that age of their normal growing up, you really can do them serious damage, in my opinion."

At the time, Cowell was a judge on The X Factor, notorious for his scathing put-downs, earning him the nickname Mr Nasty. But in the interview, unearthed by Chas Newkey-Burden during research for his unauthorised biography of Cowell, the multimillionaire impresario reveals his discomfort when criticising children. "I go into this show as a grown-up and I like to treat people like grown-ups. I find it very difficult sometimes saying to a 16-year-old what I really think because they're just not mature enough to deal with it.

"I don't think it benefits anybody – me, them, the audience at home."

Hopefuls for this year's £100,000 prize, which also guarantees a slot in the Royal Variety Performance, include 10-year-old Chloe Hickinbottom. She will be singing "White Cliffs of Dover", although Vera Lynn has said she is too young to be singing the song. Another contestant is Kieran Gaffney, a 13-year-old drummer.

Talkback Thames and Syco, the production companies behind the show, are reported to have increased support for young contestants after last year when Aidan Davis, 11, a street dancer from Birmingham and Hollie Steel, a 10-year-old singer, were both reduced to tears by Cowell. Hollie embarrassed Cowell by branding him a bully after he made disparaging remarks about her pink tutu and choice of song. There were also concerns for another of last year's finalists, Susan Boyle, who suffered an "emotional breakdown" days after the final.

Treats to look forward to this year include Max, the parrot, whose owner, Irene, attempts to feed him mashed potato, and Chandi, the "amazing dancing dog". The increase in animal acts has already caused mayhem at auditions for the co-hosts Ant McPartlin and Dec Donnell: Dec is bird phobic and Ant was bitten by a dog and chased by a pig during a Cardiff audition.

But the act generating the most column inches this year is Chloe, whose voice is praised for possessing a power beyond her years. Cowell, who has indicated he is ready to leave the show, has yet to comment on her performance. But when asked of the entertainment value of young performers in the 2004 interview, he said: "What's the point? No one at the age of 11 can really sing. There's nothing you can say to them because you can't criticise a 10-year-old."