IVF mix-ups are a regular occurrence at fertility clinics across the UK, an expert has said.

Dr Sammy Lee, a scientific consultant at the Portland Hospital in London, said the case of a white woman giving birth to black twins which hit the headlines earlier this month is probably not an isolated incident.

Every day, someone somewhere in the UK is inadvertently messing Dr Sammy Lee

Dr Lee, writing in The Scotsman newspaper, said it was vital that training was improved for doctors working in the field of in-vitro fertilisation.

He said: "Every day, someone somewhere in the UK is inadvertently messing up, but luckily the chances of it producing an obvious error of the `black twins, white twins' type is low.

"It is not enough to bury our heads in the sand and to say, `It's a one-off and won't happen again',"

Wrong embryos

Dr Lee said he was aware of regular mistakes at IVF clinics across the country.

"I am aware of the wrong embryos being transferred to the wrong patients at several NHS units during the past 10 years.

"I have also confidentially been told about a number of cases where the wrong sperm were used to inseminate eggs."

He said he also knew of cases where eggs were damaged and that eggs and embryos sometimes landed up in the wrong containers.

He demanded new standards for assessing the competence of staff specialising in the that particular field.

He also called for the establishment of independent quality control teams to ensure adherence to correct procedures.

Dr Lees said that the 27,000 UK couples who try for IVF treatment every year in the UK should be warned of possible errors.

The Association of Clinical Embryologists told The Scotsman that IVF staff expertise levels were already checked as part of clinic licensing.

Chairwoman Dr Karen Turner, said: "There are measures in place, but there is the potential for human error and we are not complacent."

Scottish member of parliament Nicola Sturgeon, health spokeswoman for the SNP, called for inquiry into Dr Lee's allegations.

She said parents must have the right to know if there has been a mix-up in their IVF treatment.