A group of ethnic minority doctors has launched legal action against the doctors' watchdog over alleged inequality in GP competency exams.
The British Association of Physicians of Indian Origin (Bapio) claims there is a "significant difference in pass rates" between UK and international graduates, including those of Indian origin.
Their lawyers have started a legal bid against the regulator, the General Medical Council (GMC), and standards body, the Royal College of General Practitioners (RCGP).
They claim the test, which confirms a doctor has satisfactorily completed speciality training for general practice and is competent to enter independent practice - known as the MRCGP exam - is flawed and discriminates against international GP trainees.
Bapio said its lawyers are seeking a judicial review of the way the RCGP conducts the test, because there is a "significant difference in pass rates which cannot be explained by a lack of any knowledge, skill or competency on the part of the International Medical Graduates (IMGs)".
Bapio argues that international graduates will have already passed a rigorous GMC examination for entry into GP training and ongoing assessments, known as the Plab test.
The body said RCGP figures show that 65.3% of international graduates failed their first attempt at the Clinical Skills Assessment (CSA) component of the MRCGP exam in 2011/12, compared with 9.9% of UK graduates.
In 2010/11, 59.2% of the international graduates failed at the first attempt, compared with 8.2% of UK graduates, while in 2008, 43% of IMGs failed the CSA compared with 8.3% of UK graduates.
A spokesman said: "These doctors are failed in spite of the fact that they will have had supervised training for three years during which time each of them would have seen on an average 3,000 patients without any complaints.
"To reach this stage they would also have had good feedback from trainers and colleagues and would have passed the theory test."
Dr Ramesh Mehta, president of Bapio, said: "Patient safety is paramount.
"These doctors have had extensive interaction over a period of many years with their trainers and patients without significant concerns.
"For them to be judged to be so grossly incompetent in a short exit exam either reflects poorly on years of training, which is unlikely, or it is because the exit exam is flawed.
"Training a doctor to be a GP costs the UK taxpayer £488,730 per doctor, which seems a profligate waste of resource considering that an estimated 300 doctors since 2010 have been removed from training because of their failure to pass the CSA.
"Legal remedy has always been our last resort. We hope that the judicial review will help to expose flaws in the system."
A spokesman for the GMC said: "It would be inappropriate for us to comment on any ongoing or possible legal action."