The head of the Royal College of Nursing (RCN) has said he "utterly rejects" a Government claim that opposition to the health Bill is actually about pensions.
Dr Peter Carter reacted angrily to Health Secretary Andrew Lansley's claim that the RCN was "having a go" about pay and pensions.
Yesterday, all the major health unions - representing doctors, nurses and midwives - stressed their "outright opposition" to the Health and Social Care Bill, currently going through Parliament.
They have expressed concerns about reforms in the Bill, including allowing NHS hospitals to raise up to 49% of their income from private patients.
They argue that the Bill dramatically increases the role of the private sector in providing healthcare and is destabilising the NHS.
All agree that doctors and other staff should be given a role in organising services but say the Bill in its current form is costly and not in the interests of patients.
Mr Lansley told BBC Breakfast this morning that opposition to the Bill was more about issues of pay and pensions.
He said the legislation was "essential in order to give nurses and doctors clinical leadership".
He added: "I'm afraid the only thing that has happened in the last few weeks that has led to this situation with the Royal College of Nursing is that the two sides of the Royal College of Nursing have shifted.
"They used to be a professional association that was working with us on professional issues and will carry on doing that, but now the trade union aspect of the Royal College of Nursing has come to the fore, they want to have a go at the Government - I completely understand it - but they want to have a go about things like pay and pensions."
He said the Government had consulted widely with staff about the Bill.
"Through the NHS Future Forum we have been out there, making sure, and doing it ourselves time and again, that we're taking staff with us in terms of understanding these issues.
"And the RCN and the RCM (Royal College of Midwives) are very clear that they support the principles of the Bill. What they are actually unhappy about is pay, pensions and jobs. I complete understand that.
"But if there were no Bill the same issues would have to be addressed. We inherited a deficit, we are having to manage the NHS within limited increases, but actually next year the NHS budget is going to go up by 2.8%."
However Dr Carter, RCN chief executive, rejected this argument.
"We utterly reject the claim that the RCN's decision to oppose the Health and Social Care Bill was based around the proposed pension changes.
"Nurses want to provide the highest possible standards of patient care and it is at the heart of everything they do.
"However, members up and down the country are telling us that this Bill is seriously destabilising the NHS.
"Equally, we know that tens of thousands of posts are being lost throughout the NHS, which is putting patient care in jeopardy and that there is now a fundamental imbalance between competition and collaboration within the NHS."
He said carrying on with the reforms - at a time when the Government has told the NHS it must find £20 billion in efficiency savings is "quite simply, the wrong thing to do".
He added: "We are disappointed that the Secretary of State would suggest that nurses and healthcare assistants would put self interest before that of patients."
Yesterday, the RCM said the the Bill was "divisive and costly".
Chief executive Cathy Warwick said: "This Bill is a massively expensive distraction from the challenges that the NHS faces in trying to improve healthcare at a time of severe spending restraint.
"The Royal College of Midwives supports many of the Government's aspirations for the NHS, such as clinically-led commissioning, greater engagement of service users in their care and more integrated services, but the fact of the matter is that these can all be achieved without the need for this divisive and costly Bill.
"Independent analysts have calculated that implementing the provisions in the Bill will cost the NHS an extra £2 billion to £3 billion on top of the £20 billion in efficiency savings the NHS has to find in the next four years.
"The Government has failed to present sufficient evidence that its proposals are necessary. They have failed to present evidence that the upheaval will result in an improvement in services to the people of England. And, they have failed to answer the concerns of the people who fear for the future of the NHS under these plans.
"Breaking up what we have, embracing the private sector, and injecting full-blown competition and market forces is not what the NHS needs or what health professionals and patients want.
"We join the growing chorus of voices calling for the Bill to be withdrawn, and the proposed reforms stopped in their entirety."
Unite's head of health Rachael Maskell said: "It is wrong and misleading of the Health Secretary to muddy the waters by claiming that the opposition to the Bill is linked to the current dispute over public sector pensions.
"This Bill is a completely separate matter which health professionals have considered very carefully and now decided that this Bill is flawed and should be scrapped.
"Doctors and now nurses and midwives have now joined all the other professionals - pharmacists, scientists, health visitors, hospital chaplains, and speech and language therapists - in opposing the Bill."
Unison's head of health Christina McAnea said: "Nurses, midwives, professional bodies and patients are all warning that this Bill is a danger to the NHS as we know it.
"This Bill will lead to fragmentation, instability and inequity in the NHS.
"It is wasting billions of taxpayers' money in pointless bureaucracy, as health workers lose their jobs, waiting lists grow and operations are cancelled."