The NHS has become increasingly dependent on doctors who have trained overseas according to a latest research paper published in British Medical Journal.
The latest analysis, published on bmj.com, found that 15% of consultants appointed during 1964-91 were trained overseas.
Doctors who qualified abroad now represent nearly a quarter (24%) of all consultants appointed since 1991, the researchers said.
These doctors are also particularly used to fill posts that UK-trained medics do not want, such as in geriatric and sexual health medicine, according to the research by Oxford University.
The workforce analysis follows continued rising trends in foreign doctors joining the British medical register. Last year 13,926 doctors joining the General Medical Council's register came from overseas, compared to 4,730 who were trained in the UK.
Doctors' leaders have raised concerns that overseas doctors coming to work in Britain are denied the chance to climb the career ladder, despite helping to keep the NHS afloat.
The British Medical Association (BMA) says that the majority of the 12,000 UK medics known as staff and associate specialists (SAS) gained their medical qualifications abroad.
These doctors then have difficulties getting on the career training ladder to become consultants when they arrive in the UK.
The bmj.com study found in contrast, UK-trained doctors from ethnic minority groups follow similar career paths to UK-trained white doctors.
By contrast, younger generations of UK trained doctors from ethnic minority groups have similar career destinations to those of UK trained white doctors, suggesting that differences in career destinations between white and non-white consultants are linked to having trained abroad rather than ethnic origin.
The percentage of UK medical graduates from ethnic minority groups has increased substantially from about 2% in 1974 and will approach 30% by 2005. White men now comprise little more than a quarter of all UK medical students and are substantially under-represented in the current intakes to UK medical schools.
The researchers said this suggested that differences in career destinations between white and non-white consultants were linked to having trained abroad rather than ethnic origin.
This raises important questions for policy makers, say the authors: should the ethnic mix of intake into medical schools broadly reflect the ethnic mix of the community from which students are drawn? If so, what should be the mechanisms to achieve such representation?
Michael Goldacre, Professor of Public Health, UK Medical Careers Research Group, University of Oxford, UK
(Country of training and ethnic origin of UK doctors: database and survey studies)