Senior hospital doctors have slammed key government polices on the NHS.
Consultants were overwhelmingly opposed to the policies
Doctors at the British Medical Association's annual consultants conference said new fast-track surgery centres were a threat to patient care.
They also claimed that plans to pay hospitals a fixed fee for the first time for treating patients would lead to the break up of the health service.
Health Minister John Hutton has rejected the criticisms saying the changes benefit patients.
Treatment centres are being set up across England. Ministers hope they will help cut NHS waiting times.
Twenty-six NHS-run centres are already up and running, along with 20 privately-run centres which provide care for NHS patients.
The centres are carrying out non-urgent operations, such as knee, hip and cataract operations.
But doctors at the BMA conference in London slammed the scheme.
They said the centres were "cherry-picking patients" and leaving NHS hospitals with the most complicated cases.
They expressed concerns about the quality of care being provided by doctors at the centres, many of whom have been brought in from overseas.
They also warned that the scheme could hit medical training, with junior doctors unable to develop skills by carrying out routine operations.
"They have created considerable problems for us," said Mr John Carvell, chairman of the BMA's orthopaedics subcommittee.
"It's all about cost, not patient care," said Dr John Hyslop, a consultant radiologist at Royal Cornwall Hospitals NHS Trust.
The government's plans to introduce fixed prices or tariffs for NHS operations also came under fire. The tariffs will be phased in across England over the next four years
But doctors at the conference overwhelmingly rejected the scheme.
"The market is going to be used to break up the NHS from within," said Mrs Anna Athow, a consultant surgeon at North Middlesex University Hospital in London.
"This is the start of the privatisation of the NHS."
Dr Paul Miller, chairman of the BMA's consultants committee, said: "I have great anxiety over where payment by results and tariffs are leading."
Consultants also attacked the government's plans to give patients a choice over where they are treated.
Dr Jackie Davis, a consultant radiologist at London's Whittington Hospital, said the policy was about "introducing the free market in the health service".
"It is a smokescreen for the government's intention of privatising the NHS," she added.
In a policy U-turn, the conference also attacked the government's PFI scheme, which uses money from the private sector to build new NHS hospitals. Doctors said it was leaving trusts with huge bills.
Mr Hutton dismissed the claims.
"The NHS is not being privatised, but we are using the independent sector to increase NHS capacity.
"The independent sector treatment centre programme is about providing speedier surgery for patients, relieving their pain, and offering them a choice of where they are treated, by providing extra capacity for NHS patients."
Meanwhile, a survey by the BMA has found that one in four hospital trusts in England have still to implement the new consultant contract.
The contract was backed by doctors in a nationwide vote in November.
"Many trusts are obviously dragging their feet because they are unwilling to pay doctors for the work they do," said Dr Miller.
"Ultimately, it will be patients who suffer - if clinics close because hospitals won't pay their consultants to run them it will mean longer waits and fewer patients being treated."