Calls to create a 24/7 “Tesco NHS” are ridiculous, according to the leader of the British Medical Association (BMA).
Dr Mark Porter said it was simply not possible when the health service could “barely afford its current model”.
Dr Porter spoke out at a BMA conference amid calls to create the same standard of care in hospitals at weekends and nights as during normal hours.
Delegates at the same meeting also passed a vote of no confidence in Health Secretary Jeremy Hunt.
The NHS has made 24/7 care one of its key priorities in its review of urgent and emergency care.
Data shows that mortality rates increase during out-of-hours provision.
Last week NHS England highlighted figures that showed if the same standard of care could be provided seven days a week more than 4,400 lives could be saved each year.
There have also been suggestions routine care – non-emergency operations such as knee and hip replacements, for example – should be made available.
But Dr Porter told the BMA’s annual conference in Edinburgh: “Like many doctors here, I feel personally offended by the terms in which this debate has been couched.
“Like many of you I work nights and weekends as well, at time when much of the private sector is fast asleep and ministers are tucked up soundly in their beds.
“Let us be clear. We all want urgent care at weekends and evening to be of the same high standards as patient can expect on weekdays.
“But the calls we sometimes hear for a Tesco NHS, full service, 24/7, are just ridiculous when the health service can barely afford its current model.”
London GP Dr Chaand Nagpaul said he agreed.
“It is utter folly to compare the NHS to seven-day supermarket working.”
He went on to say that Tesco opened on Sundays because it made a profit, but making the NHS provide a comprehensive service at the weekend would cost money for a “public service with a fixed inadequate budget”.
He added it was a “luxury the NHS simply cannot afford”.
Dr Porter also warned that doctors were struggling to make an impact in the new NHS.
Reforms to give medics more power to shape health services were introduced in April.
But Dr Porter said a combination of cuts, red-tape and relentless pressure meant they were often finding it “impossible” to make improvements.
The BMA received feedback from 1,000 medics about the current conditions.
Nine in 10 complained they had faced obstacles when trying to make improvements.
Half cited a lack of time as a barrier, 39% financial constraints and a third too much bureaucracy.
Mr Porter said: “It is a grave cause for concern.”
Addressing the concerns about the current working environment for doctors, Health Minister Dr Dan Poulter said he accepted the health service was facing challenges.
But he praised the work doctors were doing.
“Doctors are working extremely hard and continue to provide a high quality of care in the face of rising healthcare demands. It is thanks to this hard work that the NHS is performing well.”
And in a sign of just how angry doctors are, delegates at the conference also passed a vote of no confidence in Health Secretary Jeremy Hunt.
Jacky Davis, a hospital consultant, told the conference: “We have been betrayed.”
Last year they also passed a vote of no confidence in then Health Secretary, Andrew Lansley.