Family doctors have threatened court action to prevent a newly launched smartphone video consultation service from going ahead.
Delegates at the British Medical Association's annual GP's conference said the new GP at Hand service, which offers remote appointments within two hours, risked "favouring the well above the ill".
Run by technology company Babylon, the service became available to millions of patients in London on Monday and will soon extend across the country.
The firm is encouraging patients to switch from their current GP surgery, which critics said risked "cherrypicking" the most healthy while depriving practices of the money needed to care for those with more complex illnesses.
Last night the BMA conference criticised the use of public money "to promote inequitable access to NHS branded services" and threatened judicial review to thwart the new scheme.
It came as GPs expressed concern over wider plans to introduce online appointments, saying they risk excluding the elderly.
Dr Susie Bayley, opposing GP at Hand, warned: "A service that favours the well above the ill is morally questionable. This will lead to huge inequity."
With the backing of NHS leaders, increasing numbers of GP surgeries are being encouraged to provide more remote consultations.
However, family doctors believe the initiatives often increase doctors’ workloads because many patients remotely consulted are then invited in for a face-to-face appointment.
While adopting online consultation is currently voluntary and a matter for individual practices or groups of practices, doctors have warned of “creeping coercion” and of funding becoming conditional on embracing the formats.
“It’s quite a sexy new area of medicine and seems to be flavour of the month, but perhaps access for people who are really sick is more important than providing instant advice for those who have a cough or a cold,” said Dr Naomi Beer, an East London GP, who successfully led a separate motion expressing concern about "the creeping coercion" on GPs to consult online.
“It’s going to be a younger, generally more healthy population who are going to use this.”
Last motion of the day at #lmcconf being proposed by @susiebayley of @DerbyLMC and she is very clear about how unacceptable a cherry picking GP service is in relation to @GPatHandpic.twitter.com/QtsMDZmZFf— Krishna Kasaraneni (@Dr_Kasaraneni) November 10, 2017
A spokesman for the BMA said: “It is important that any new system of registering patients does not damage the financial stability of GP practices and delivers safe, effective care on an equal basis for all patients wherever they live.
"This motion reflects the need for greater clarity on how these new proposals should work and the BMA will be seeking to meet those involved to discuss a way forward”
NHS England has defended the service, saying: "This particular GP practice has developed this patient offer which is included as part of their existing standard GMS service for their registered patients.
"The practice is subject to all the data protection and information security rules applicable to any NHS practice."