The UK’s fertility regulator has launched an investigation into claims that at least four British doctors are helping couples to choose the sex of their babies.

Hundreds of couples are allegedly paying up to £14,000 for a sex selection service, despite the practice being illegal under UK law for non-medical reasons.

The allegations, published in the Daily Mail, say prospective parents are accessing treatment through private clinics nationwide, including at Harley Street in London. The doctors allegedly perform initial tests in the UK before sending couples abroad to clinics in locations including Crete, Cyprus and Dubai.

The Human Fertilisation and Embryology Authority (HFEA) said in a statement it would be “extremely concerned about any HFEA licensed centre, or any individual connected to it, promoting and facilitating such treatment”.

Three of the four doctors identified in the report said there was no need for patients to tell their GPs if they were pursuing gender selection.

Rafet Gazvani, an NHS consultant based at Liverpool Women’s hospital, offered the service through his private clinic. He said his NHS boss would have a “heart attack” at the prospect of a patient travelling abroad for gender selection.

He told the Mail: “I think everyone should be allowed, under controlled circumstances, to do it. I’m doing what I believe and I’m old and established enough to be able to fight my corner.”

Contacted subsequently for comment, Gazvani said: “I understand some people may have moral issues relating to gender selection in fertility treatment.

“However, during the consultation, when these were discussed, I did try to emphasise that there are many reasons people may choose to undergo such treatment abroad and that is an individual’s choice.

“The consultations and treatments I provide are entirely legal and are completely separate from my NHS work.”

Prof Helen Stokes-Lampard, the chairman of the Royal College of GPs, said: “Patients must feel safe to disclose sensitive information about their health, or potentially impacting on their health, so to hear that some companies are advising patients not to disclose important information to their GP is deeply concerning. Any situation where you are advised not to share information with a trusted healthcare professional should set alarm bells ringing.”