Billy Elliot - The Musical is expected to reach the stage this autumn

The movie's director Stephen Daldry will direct the theatre musical, and is hunting for three boys to follow in the footsteps of the film star Jamie Bell.

Daldry told BBC Breakfast: "They've got to be exceptional children." Sir Elton John has written the show's music.

Some auditions were held in January, with more this month in London, Glasgow and Nottingham.

The potential stage stars need to have excellent tap, ballet and contemporary dance skills plus exceptional singing as well as gymnastic abilities, Daldry said.

Details of Billy Elliot - The Musical auditions on BBC Breakfast

"So the demands are even more acute within the stage musical than they were for the film," he said.

Producers need three actors at the same time because one child could not be made to perform in eight shows a week, he said.

And those stars would be replaced after six months, he added, so the audition process would go on and on.

"We try to find the spirit of the child - because the child needs to have a certain amount of charisma to hold down a whole West End show," he said.

"So you need to try to explore the child very quickly within the audition process, just to see what sort of energy, what sort of stage confidence, what sort of motor a child has."

The show would reach the stage in the autumn, he said, and Sir Elton was the person who provided the motivation to turn the film into a theatre show.

"He came to see one of the early showings of the film and his response was so strong, he really came up with the suggestion 'is there anything we can do on stage?'"