Opera legend Dame Kiri Te Kanawa fears many young singers are starving themselves and ruining their voice because they are under so much pressure to look good on stage.

The 69-year-old soprano is convinced modern opera stars now put their appearance ahead of their vocal abilities, and admits she was shocked to see the state of some singers who are terrified of gaining weight.

She tells Britain's Radio Times, "When I was at the Met (Metropolitan Opera in New York), I would see these young girls, starving hungry but terrified to put on weight. They couldn't even go down to the canteen and eat in front of anyone because they were being watched. You can't do that. You've got to have beef on you if you're going to sing. I was never really hugely big, but I certainly weighed more than I do now. I ate to sing."

She adds, "Sometimes they're more beautiful than their voice, and that's a bit of a sadness..."

The New Zealand star also reveals she is wary of new opera singers who are discovered overnight on reality Tv shows, because she is convinced professional vocalists need proper training to perform at a high level.

She adds, "I'm always wary of someone who is a bus driver and decides, aged 28, that they want to be a singer. There's got to be a period of study, from age 16 to 22, and then it moves along. You can't just think, 'Oh, I can sing in the bathroom, I'll be fine tonight on stage'. Not at all. There is such a demand on the voice for it to be able to produce night after night. It's the building up of the muscles that make that pair of vocal cords really work."