Figures published on Wednesday by NHS Digital show that the full-time equivalent (FTE) GP workforce dropped by 445 in the three months to 31 December 2016, a fall that came on top of a decline of nearly 100 over the previous year.
The independent doctors and dentists review body (DDRB), which advises the government on doctors' pay, warned in a report on Tuesday that it was 'unclear' how GP services could be maintained over the coming five to 10 years in the face of the growing workforce crisis.
GP leaders said the latest official workforce data were a 'huge blow' for general practice, which underscored how far the NHS was from hitting the government's target of increasing the GP workforce by 5,000 by 2020/21.
RCGP chair Professor Helen Stokes-Lampard said: 'These figures are a huge blow – especially considering the recent efforts we know have gone into building the GP workforce.
'At face value a drop of over 400 FTE GPs based on figures to December is dreadful when we so desperately need thousands more in order to cope with ever-growing patient demand.
'We need to turn the tide. The future of the health service and patient care relies on having a robust general practice, with enough GPs to deliver the care and services our patients need.'
Professor Stokes-Lampard warned that 'current efforts to recruit more GPs and make general practice an attractive profession must be stepped up further' and pledging that the college would continue to work with Health Education England and other organisations to help 'wherever we can'.
BMA Education, Training and Workforce GP lead Dr Krishna Kasaraneni said: 'These figures underline just how far we are from meeting the government’s own target of recruiting and retaining more GPs as we near the one-year anniversary of the GP Forward View in England.
'Despite the constant promises from ministers that the GP workforce would be increased by 5,000, the number of FTE GPs has fallen once again while the overall number has stagnated. While there have been encouraging increases in other healthcare professionals in general practice, what we really need are GPs who can deliver more appointments and other frontline services to meet rising patient demand.'
Dr Kasaraneni warned that the triggering of Article 50 to begin the UK's exit from the European Union on Wednesday could add to the workforce crisis in general practice and the wider NHS.
'With almost half of the 10,000 EEA doctors working in the NHS considering leaving the UK because of the referendum result this could further reduce the number of GPs delivering care in the NHS,' he said.
'The NHS is at breaking point and it is not acceptable for this recruitment and retention crisis to be allowed to get worse. It is time for the government to act urgently to implement the GP Forward View with its pledge to deliver a long-term, sustainable plan for a well-resourced and appropriately staffed general practice.'
Professor Stokes-Lampard added: 'New initiatives to improve retention in our profession – such as those the college presented to the government last year - must be conceived and implemented urgently. We are committed to working with NHS England and the government to ensure GPs stay working in the profession.
'There is better news in Wales with a slight increase of GPs over the last year – and we are encouraged to see a significant increase in the practice nurse workforce, and over 850 more other primary care professionals enter our workforce over the last year.
'General practice can be the best profession in the world, but GPs need greater support and investment in the service to enable them to do their jobs properly for the benefit of patients, and the wider NHS.
'A key pledge in NHS England’s GP Forward View was to deliver 5,000 more full-time equivalent GPs and 5,000 other primary care professionals by 2020. Despite today’s figures being incredibly disappointing, this remains a goal worth fighting for, and we all must redouble our efforts to achieve it.'
A DH spokeswoman said: 'GPs are the absolute bedrock of the health service and we remain committed to an extra 5,000 doctors in general practice by 2020. We have made important strides over the last year to improve conditions to attract more GPs - such as paying a large amount of GP indemnity costs, cutting red tape, agreeing a new contract with their union to deliver a 1% pay rise, as well as bringing in new schemes to help GPs work more flexibly towards retirement.
'We currently have the highest number of GPs in training than ever before, and we know that it will take time for this to impact on GP workforce numbers.'