The figures, which show the extent of NHS reliance on overseas doctors in primary care, come as health secretary Jeremy Hunt prepares to set out plans to make the health service 'self-sufficient' for doctors.
In his speech at the Conservative party conference on Tuesday, Mr Hunt will unveil plans to expand medical training places and cut NHS dependence on doctors recruited from abroad, along with a four-year mandatory term of NHS service for medical graduates in England.
Mr Hunt will say: 'Currently a quarter of our doctors come from overseas. They do a fantastic job and we have been clear that we want EU nationals who are already here to be able to stay post-Brexit. But is it right to import doctors from poorer countries that need them whilst turning away bright home graduates desperate to study medicine?'
Mr Hunt is expected to say that his plans will make the NHS self-sufficient for doctors by the end of the next parliament. But analysis by GPonline of GP workforce data from NHS Digital reveal the huge role overseas- and EU-trained doctors currently play in keeping the NHS running.
In NHS Barking and Dagenham, London, just over 66% of GPs were trained outside the UK. In 14 out of England's 209 CCGs, more than half of GPs trained outside the UK, and nationally more than one in five GPs were not UK-trained.
In NHS Bassetlaw, in the Yorkshire and Humber NHS region, nearly a third of GPs were trained outside the UK. Half of these doctors were trained in other EEA countries, and half in other parts of the world.
The NHS workforce data show that 21.3% of GPs in England trained outside the UK. Of 30,336 GPs whose country of qualification was known, 1,296 qualified outside the UK but in the EEA, while 5,178 qualified outside the EEA.
Mr Hunt's conference speech follows comments in a Mail on Sunday interview in which he said that Brexit could offer a chance for the NHS to cut back its reliance on doctors recruited from outside the UK.
He told the newspaper that quitting the EU would ‘throw into sharp relief the number of doctors, nurses and healthcare assistants we need to import every year in order to sustain our health system’.
Mr Hunt added: ‘I think people will ask whether it is right when we are turning away bright British youngsters from medical school – who might get three A-stars [at A-level] but still can’t get in – at the same time we are importing people from all over the world. I think it’s a debate we need to have.’
In a blog earlier this year, GMC chairman Professor Sir Terence Stephenson wrote that leaving the EU should not have any impact on doctors already on the register. But the GMC and the government are yet to clarify how EU doctors who wish to work in the UK will be affected in future.