Image caption GP consortiums should be up and running by 2013

The scale of health reforms being made in England has taken the NHS by "surprise" and could threaten its ability to make savings, MPs say.

The Commons health committee has criticised the "significant policy shift" of scrapping primary care trusts and passing control of budgets to GPs.

It said the NHS had not been able to plan properly for the reforms.

The latest criticism of the changes comes after David Cameron said public service reforms could not be put off.

In a speech on Monday, the prime minister said he wanted to "do right" by public sector workers but arguments he should stick with the status quo were a "complete fiction".

Managers working for primary care trusts (PCTs) are currently responsible for planning and buying local services, but GPs will take on responsibility for this from 2013.

Pilots are already starting and once the process is complete, two tiers of management - PCTs and the 10 regional health authorities - will be scrapped.

'Tossed a grenade'

The cross-party group of MPs on the Commons committee expressed concerns about the plans on the eve of the Health and Social Care Bill being published on Wednesday.

While they have no argument with the government about the need to ensure the NHS gets better value for money in procuring treatment, they are critical of the way ministers changed their policy.

The speed of the reforms means PCTs are imploding as staff leave in droves Dr Laurence Buckman, British Medical Association

The report highlighted what it called a "significant policy shift" between the coalition programme announced in May and the more detailed white paper in July.

It was only at the later date that it became clear both PCTs and health authorities would go, leaving GPs working in consortiums responsible for the majority of health care provided in hospitals and the community.

The MPs said this had taken the NHS by surprise and meant the service had not been able to plan properly for the reforms.

In turn, this has made the need to make savings in the health service - the target is £20bn by 2014 - even more difficult, they said.

While the health budget is increasing in the coming years, many experts say this is not happening fast enough to keep pace with rising costs from factors such as the ageing population and obesity.

The MPs' report added it did not think the plan was the "most efficient way" of delivering the government's aims to improve care, increase choice and cut bureaucracy.

One committee member - Dr Sarah Wollaston, herself a GP - said it felt like "someone had tossed a grenade" into the NHS.

Committee chairman Stephen Dorrell said it was essential the government addressed the concerns being raised.

"The health bill represents a major opportunity to get these policy questions right," he said.

'PCTs imploding'

The MPs' report comes amid mounting fears about the plans.

Modernising the NHS is vital and what we are proposing is a carefully staged transition, Andrew Lansley, Health secretary

On Monday, six health unions warned of their "extreme concerns" that greater commercial competition in the NHS would end up undermining care.

The NHS Confederation, which represents managers, has also suggested hospitals may have to close.

Professor Chris Ham, chief executive of the King's Fund health think tank, said the MPs were "right" to highlight the risks.

Dr Laurence Buckman, of the British Medical Association, said: "The speed of the reforms means PCTs are imploding as staff leave in droves and those managers who are left are focused on delivering the reforms rather than efficiency savings and the maintenance of patient care.

"We would not want to see the potential benefits of clinically led commissioning lost, and that is a risk at the moment."

Shadow health secretary John Healey added: "This is an 11th-hour warning to the health secretary to think again before he forces through this big NHS reorganisation."

But Health Secretary Andrew Lansley said the reforms would improve care and efficiency, but denied they represented a major upheaval, saying they were "simply building on the best of what already exists".

"Modernising the NHS is vital and what we are proposing is a carefully staged transition, with the ever increasing engagement of patients and NHS staff," he said.