Andrews' career was famed for her four-octave vocal range

Dame Julie, famed for Mary Poppins and The Sound of Music, told BBC One's Breakfast With Frost that she now only had "a wonderful, deep, bass voice of about five notes and that's about it".

I probably won't want to go back to singing again - I'd love to for my own pleasure but professionally I probably won't Dame Julie Andrews

She said she was heading up the research for "pioneering" work on vocal cords, adding: "I'm probably going to be too old or too occupied with a million other wonderful things to indulge."

The British-born singer settled a malpractice claim in 2000 over a throat operation she said had left her unable to sing professionally.

The terms of the settlement reached with Dr Scott Kessler and Dr Jeffrey at New York's Mount Sinai hospital were confidential.

Dame Julie had said previously that she held out hope that her voice might recover.

Her vocal problems emerged after doing 20 months on Broadway followed by taking the show Victor Victoria on the road.

She starred in Mary Poppins and The Sound of Music

"My specialist at the time said then you'd better just fix what I think is a cyst in your vocal chords," she said.

"Everybody thinks I had cancer, or nodules, it was nothing of the sort. So he fixed what he thought he should do and he did a lot more besides and the rest is history."

But the actress added that as a result, many new avenues of work had opened up to her, including directing a stage play in New York of The Boyfriend, which opens in five weeks' time.

It is the play which first took her to Broadway in 1954 and helped kick-start her career in the US.

She has also written children's books, appeared in films including 2001's The Princess Diaries, with another movie due out in the autumn.

Wholesome image

Describing her successful career, Dame Julie said: "I think I got very, very lucky but still to have, to have really had longevity is where I've been so fortunate, because quite often a career can just be over in a shot."

She added that she did not mind the wholesome image her roles in children's films such as Mary Poppins gave her, saying: "I'm sure there's a piece of me in everyone of those movies because I did do them.

"But I don't think that's the whole - at least I hope not, it would be too awful to be that sugary sweet."