Prime Minister David Cameron defended his Government's NHS reforms this morning after a group top doctors and health specialists warned they will do "irreparable harm" to the health service.
More than 400 experts sent an open letter to the House of Lords urging peers to reject the coalition's controversial Health and Social Care Bill when they vote later this month.
The letter, also sent to the Daily Telegraph, said: "The Bill will do irreparable harm to the NHS, to individual patients and to society as a whole.
"It ushers in a significantly heightened degree of commercialisation and marketisation that will fragment patient care; aggravate risks to individual patient safety; erode medical ethics and trust within the health system; widen health inequalities; waste much money on attempts to regulate and manage competition; and undermine the ability of the health system to respond effectively and efficiently to communicable disease outbreaks and other public health emergencies."
The letter includes signatories from across a wide spectrum of public health practice, including more than 40 directors of public health and some 100 leading public health academics.
Its authors added: "While we welcome the emphasis placed on establishing a closer working relationship between public health and local government, the proposed reforms as a whole will disrupt, fragment and weaken the country's public health capabilities.
"The Government claims that the reforms have the backing of the health professions. They do not. Neither do they have the general support of the public.
"It is our professional judgment that the Health and Social Care Bill will erode the NHS's ethical and co-operative foundations and that it will not deliver efficiency, quality, fairness or choice. We therefore request that you reject passage of the Health and Social Care Bill."
Mr Cameron told ITV1's Daybreak: "Of course there are doctors and others within the NHS that are wary about parts of our proposals, about greater choice for patients, about greater competition with the NHS.
"There have always been opponents to that, but the point of the exercise we held in the summer, when we paused and restarted the reforms, was to bring more of the health service on board, and many GPs, many doctors and many in the health service recognise that change is necessary if we are going to drive up standards in the health service, in which we invest and care about so much."
He added: "I think the reforms are right, I think they will improve patient care. Above all, they will be good for patients. They are going to give you more power and control over the care you get, a greater choice too, which I think patients will welcome."
Professor Martin McKee, from the London School of Hygiene and Tropical Medicine, a signatory of the open letter, said: "This letter demonstrates the widespread recognition within the public health community that this Bill is bad for the NHS and harmful to the overall health of the population."
Shadow health secretary John Healey said: "David Cameron is in denial, both about the damage his plans are doing to the NHS and the strength of opposition to his Health Bill.
"There is no mandate for the Bill, either from the election or the coalition agreement. With the Government having railroaded its plans through the Commons, heavy responsibility is now going to be shouldered by the Lords."
Dr Paul Edmondson-Jones, director of public health in Portsmouth, who also signed the letter, told the BBC Radio 4 Today programme that he believed the Bill was "quite seriously flawed", was going to be bad for both the NHS and society, and would widen health inequality.
He said: "It will lead to a fragmentation of the health service that we have at the moment. The emphasis on opening up the market to increase competition, to privatisation, will fragment the market and will make the whole basis of working together very much more difficult."
He added: "If you look carefully at the wording of this Bill, we're concerned that it takes away the absolute duty of the Secretary of State to provide a health service which is free at the point of access."
He maintained that none of the amendments had affected the substance of the Bill and the "overall ethos and direction" was still exactly the same.
"We believe that this may be the last chance now to significantly affect the passage of that Bill or hopefully have the Bill withdrawn," he said.
Professor Steve Field, who chaired the NHS Future Forum, said the Government listened and made more than 180 "substantial amendments" to the Bill "which addressed some of our concerns".
He added: "I think what we've got to try and do is look forward about how we produce a nationwide National Health Service of the highest possible quality and that is what our report helped to do."
Dr Hamish Meldrum, chairman of the British Medical Association, said: "As this letter demonstrates, doctors have major concerns about the Bill.
"Accelerating the process of marketisation poses huge risks to the NHS, threatening its ability to operate effectively and equitably.
"Insufficient thought has been given to the long-term consequences for medical education and training, public health and the patient-doctor relationship.
"Ideally, we'd like to see the legislation withdrawn entirely. Failing that, it needs to be significantly amended."
The backlash came as Lord Owen and Lord Hennessy published a letter to fellow crossbenchers outlining an amendment to the Bill.
It would allow for further scrutiny of parts of the Bill, including on commissioning of NHS services, through reference to a select committee.
It said: "We believe there has been insufficient scrutiny of parts of the massive Health and Social Care Bill and, whilst we accept it is not the role of the House of Lords to challenge the legislation in its entirety which has been given a third reading in the House of Commons, we do believe it imperative the House of Lords provide a mechanism for far greater in-depth consideration of a number of parts of this Bill which cover duties and constitutional issues."
Baroness Thornton, who leads for Labour on health in the Lords, said: "Lord Owen's amendment means an important and complex part of the Health Bill will now be subject to the close scrutiny it failed to get in the Commons.
"A committee of experts will be able to take evidence - something normal procedure in the Lords does not allow.
"They will also be able to recommend whether these parts of the Bill make sense and how they might be improved.
"Parts of the Bill, such as the failure regime - dealing with closure or sale of services and hospitals - were introduced so late in the Commons that they have not been looked at all.
"Labour will be supporting this amendment because it will allow peers to focus fully on the whole of the Bill, albeit in different ways."