BBC's Linda Duffin: The government wants to encourage whistleblowers

Managers at the Royal Brompton Hospital ordered the investigation after a complaint was made to an official looking into the deaths of 29 children at another hospital - the Bristol Royal Infirmary in the west of England.

The Health Secretary Frank Dobson confirmed an inquiry was under way but appealed for it to be allowed to take its course.

"Before anybody jumps to any conclusions they should await the outcome of these investigations.

Dobson: Let inquiry take its course

"This is being looked into promptly and it will be looked into thoroughly and I have to say I hope that it will show that the standards are very high there as one would expect."

The complaint accused an unnamed surgeon at the London hospital, part of the Royal Brompton and Harefield NHS Trust, of an inappropriate attitude towards Down's Syndrome children.

It also called into question the success rates of surgery at the hospital, which specialises in cardiac and lung surgery for both children and adults.

The trust confirmed that an external investigation by two senior paediatricians would be carried out, but insisted that the success rates at its Royal Brompton cardiac unit had repeatedly been found to be satisfactory.

'No doubt'

A spokesman said: "An anonymous complaint was made by one individual alleging an inappropriate attitude by a surgeon and that the outcomes for child surgery at the Royal Brompton were not as good as they should be.

"We believe that child outcomes at the hospital are absolutely of the nature that they should be in a leading heart centre. While we have no doubt of that, all claims of this nature must be looked in to."

The inquiry will look at a series of reports which give details of a range of cardiac surgery procedures carried out on children at the Royal Brompton, and their results.

It does not concern the heart transplant unit at the Harefield Hospital or its principal surgeon, the pioneering cardiologist Sir Magdi Yacoub.