Dr Sammy Lee, scientific consultant at the Portland Hospital in London, said last week that he is aware of regular mistakes at infertility clinics across the country. His claims followed the recent mix-up at one clinic, which resulted in black twins being born to a white couple. 'It is not enough to bury our heads in the sand and to say, 'It's a one-off and won't happen again'', said Dr Lee of this highly publicised incident. Writing in The Scotsman newspaper, he called for improved training of IVF doctors to cut the risk of further errors.

Dr Lee said he knew of embryos being transferred to the wrong patients at several NHS units during the past ten years. 'I have also confidentially been told of a number of cases where the wrong sperm were used to inseminate eggs' he added. He claims the problem stems from the way in which embryologists are recruited and trained, saying that many start soon after graduation. 'The IVF laboratory is not the place to train a rookie' he said.

Dr Karen Turner, chair of the Association of Clinical Embryologists, said that staff expertise levels were already checked as part of clinic licensing. She said there are measures in place, but that 'there is the potential for human error and we are not complacent'. A spokeswoman for the Human Fertilisation and Embryology Authority (HFEA), the UK regulatory body that issues licenses to fertility clinics, said: 'To say errors are occurring with any degree of frequency is unnecessarily alarmist'. She added that even when clinics are run extremely well and follow best practice it is impossible to give 100 per cent guarantees. The health spokeswoman for the Scottish National Party (SNP), Nicola Sturgeon, has called for an inquiry into Dr Lee's allegations.