Concerns have been raised over plans to expand the number of people working as what Health Secretary Jeremy Hunt has described as "a new class of medic".
Mr Hunt said the use of more physician associates (PAs) - usually science graduates who have undergone two years of intensive training - to perform medical duties including examining patients, diagnosing illnesses and analysing test results, will ease the pressure on doctors.
He told the Times newspaper: "The NHS is treating record numbers of people. That's why we are growing the workforce further with a new class of medic so busy doctors have more time to care for patients."
PAs are not currently obliged to be registered with a regulator but the NHS Careers website indicates work is under way to bring in statutory registration for the profession.
There are already PAs working in the Midlands, London, Weston-super-Mare, Bristol, and parts of Scotland, and new training courses are due to begin next month at t he University of Worcester and University of Wolverhampton, and next year at Plymouth University Peninsula School of Medicine.
Katherine Murphy, chief executive of the Patients Association, told the Times there are concerns that hospitals will become reliant on employing more PAs because they are paid less than fully qualified doctors.
Ms Murphy said that there is a fear the medical profession is following in the footsteps of nursing, where she said healthcare assistants are sometimes hired in place of nurses.
Mark Porter of the British Medical Association said the new medics could be useful, but asserted that the new posts should not be used as a way of replacing doctors.