THE government’s IVF watchdog is “not fit for purpose” and must be reformed, according to the head of an official inquiry into an embryo mix-up in which black twins were born to a white couple.

Professor Brian Toft, who was asked by the government to chair an inquiry into the 2002 scandal, was prompted to speak out after The Sunday Times revealed last weekend that women’s eggs were fertilised with the wrong sperm at one of Britain’s leading hospitals earlier this year.

The embryos of three women being treated at Guy’s and St Thomas’ Hospital in London had to be destroyed and their cycles of treatment abandoned following the bungles in February.

Toft, professor of patient safety at Coventry University, has written to Sir Liam Donaldson, the chief medical officer, warning that the Human Fertilisation and Embryology Authority (HFEA) is failing to protect the 37,000 women who have fertility treatment every year. The HFEA is responsible for regulating IVF clinics.

Toft said: “I cannot imagine what it must have been like to be undergoing that kind of treatment and then for someone to say ‘We haven’t done the job properly and, as a consequence, you have lost your embryos’. It is just beyond belief.”

In his letter to Donaldson, he wrote: “The HFEA should be reformed if it is ever to be fit for purpose”.

Toft has also written to Alan Johnson, the health secretary, demanding an investigation into the mix-up at Guy’s and St Thomas' in February. He has asked the government to investigate the failure of the HFEA to prevent the mix-up and take tough action against the clinic.

One of the mix-ups at Guy’s and St Thomas’ hospital was discovered when the embryologist realised she had used a sample from the wrong man to fertilise a patient’s eggs.

Within days of this mistake, another error came to light when scientists carrying out tests designed to ensure that babies are free of hereditary diseases found genes showing that the embryos could not belong to the people they had believed to be the parents.

The tests, called pre-implantation genetic diagnosis, are only carried out on a minority of embryos. Fertility doctors fear further errors could have occurred that have not been detected.

Couples who have had babies following IVF treatment at Guy’s and St Thomas’ are contacting the trust demanding assurances that they were not the subject of a mix-up.

One concerned mother said: “We are absolutely shocked that they never wrote to us to warn us.”

It is understood that an embryologist at Guy’s and St Thomas’ warned the trust it was running the risk of errors in 2006. The whistleblower is believed to have been forced to leave the trust after highlighting the problems.

A spokeswoman for Guy’s and St Thomas’ said: “Earlier this year we recognised a potential problem and, as is standard practice for us, we conducted a thorough internal investigation and informed the HFEA. Following this investigation, we are currently considering if there is a need for independent audits.”

Alan Doran, chief executive of the HFEA, said: “It is not the case that we have failed to investigate serious incidents at Guy’s, nor is it the case that we have not implemented the Toft recommendations. But, of course, we can always do better and we welcome the chance to work with those who can help us improve.”

Readers with further information or comment on the IVF mix-ups can write to health@sunday-times.co.uk

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