In parts of the country NHS England's area teams have cut occupational health funding and warned practices that 'the cost of these services now falls within your employment responsibilities'.
NHS England has launched a review to standardise occupational health services for GPs across England, but has identified the services as 'possible quality, innovation, productivity and prevention (QIPP) opportunities' for savings.
GPs fear the review could trigger further cuts to long-standing services formerly funded under PCTs.
Medical directors for the two NHS England area teams covering Durham, Darlington and Tees, and Cumbria, Northumberland, Tyne and Wear wrote to GPs in April to confirm that 'access to occupational health contracts commissioned by PCTs expired on 31 March'.
Practices could continue to refer to the service but 'will now be charged'.
Cleveland LMC secretary Dr John Canning warned the cuts would force some GPs to quit, or leave those off sick unable to obtain treatment. 'It is a tragedy for them, their families and their patients,' he said.
Cornwall LMC's Dr Beth McCarron-Nash said she feared funding cuts to 'excellent' occupational health services in the south-west of England. She warned NHS England against 'standardising things downwards rather than up'.
'Our occupational health service has said the number of GPs being sent or self-referring to the service has doubled in the past year,' Dr McCarron-Nash said. 'When GPs feel under pressure, one of the first things to go is their health.'
It was 'vital' to support GPs reporting stress at a time when there is a national shortage of GPs, she added.
GPC negotiator Dr Dean Marshall said funding occupational health was vital as rising workload and decreasing resources put pressure on GPs.
'It would appear this is something that people think is an easy thing to cut,' he said. 'It is a mistake to do so.'
A spokeswoman for NHS England said: 'The evidence of increasing stress in the primary care workforce is a compelling reason why we wish to ensure occupational health services are available for primary care staff.
'NHS England is seeking to develop a single approach across area teams.'