Opera singer Cynthia Lawrence is limbering up to perform a death-defying leap for her art.

When most divas reach the end of Puccini's tragic opera Tosca, they disappear delicately off the back of the stage - even though the story calls for a suicide jump from the top of the Castel Sant'Angelo mausoleum in Rome.

But in true commitment to the role, American Lawrence is practising to dive 20 feet, so it will look as though she has fallen behind the orchestra pit at the Royal Albert Hall.

Impresario Raymond Gubbay had already signed up two acrobats to do the leap after designers conjured up an imaginative sleight of hand for a dramatic conclusion.

The plan, which will still be used for performances without Lawrence, was for the soprano to run up a ramp to a guardhouse where she is replaced by a stunt double for the death scene. But Lawrence, a mother-of-two, insisted on performing the jump herself- - as she has done in productions elsewhere.

"I've always jumped," she said. "There are famous sopranos who never jump, but not me.

"I draw on experience - I used to do trampolining and high-jumping. You feel invigorated and jazzed by it all."

The singer, who shares the role of Tosca with Paula Delligatti, has never jumped as far as she will in this production.

She said: "It's pretty hairy, it really is. With the costume and the show and the lights and the adrenaline, you have to slow things down in your head so you hit exactly the same mark every time."

Her training is being overseen by consultant Nik Litton of Aircraft Circus, whose previous work included the acrobatic performers for The Lord Of The Rings stage show. He was surprised to discover Lawrence intended to do the jump after singing for two and a half hours.

"I was even more astonished when I realised she was capable of doing it," he said.

Gubbay said: "I thought it was a bit of a wind-up when I heard. It's extraordinary.

"Normally they [Toscas] do just a little dainty jump the other way and it's not terribly convincing. I think this will take people's breath away."

Tosca opens at the Royal Albert Hall on 28 February and runs until 9 March. Booking: 020 7838 3110.