Controversial advice by a senior GP to would-be family doctors to act "less overtly gay " if they wanted to pass exams provoked a storm of protest yesterday as the Royal College of General Practitioners (RCGP) started its inquiry into the affair.

The remarks by Dr Una Coales, a member of the RCGP council, in a guide for aspiring GPs shocked senior members of the profession who warned such an approach was unacceptable.

But others came to her defence, suggesting her comments had shone a light on a persistent and unsavoury bias in the selection of students.

Dr Coales, a GP in Lambeth, south London, suggested gay students speak in deeper voices and alter their body language to increase their chances of success in the RCGP's Clinical Skills Assessment.

A friend of Una Coales said: "This guide has been in circulation for three years. It is the first time the RCGP has reacted to it. She is an outspoken Conservative woman doctor and someone out there doesn't like that and is getting at her. She is a good person and does not understand why she has been victimised. She has been an active campaigner on behalf of gay doctors and nurses and all minority groups and in her view the Royal College has made great progress in its attitude to minorities ."

In her guide, Dr Una Coales's MRCGP CSA Book, she also advised Nigerian and Asian trainees to "focus on the lyrical Scottish or Welsh accent" if sitting exams in these regions. Female candidates were advised not to wear floral dresses, male candidates to shave off their beards and overweight students to "project an image of Santa Claus."

The guide was published three years ago and serialised in a medical magazine but the remarks did not attract attention until they were tweeted by another doctor earlier this week.

Among those who responded, David Haslam, immediate past president of the British Medical Association and a past president of the Royal College of GPs tweeted: "I was shocked and appalled to read about Dr Una Coales. She should be deeply ashamed. Attitudes like this have no place in medicine."

However, Lindsay Moran, a GP in Leeds and treasurer of the Yorkshire faculty of the RCGP responded : "Whatever people's views on Una Coales' comments, she highlights important bias against students/doctors that needs more consideration."

Research into discrimination against foreign doctors published in the 1990s showed that having an Indian-sounding surname halved a doctor's chances of getting a job interview. Sam Everington, who authored the studies, told The Independent: "There is no sense that things have changed."

Neil Hunt, chief executive of the RCGP denied allegations of bias. "We take equality and diversity extremely seriously and through our examiner and role-player training and quality assurance programmes aim to ensure that no candidate is discriminated against."