Government health reforms are "potentially damaging" for patients and risk undermining the stability and long-term future of the NHS, medical leaders have suggested.
The British Medical Association (BMA) urged the Government to avoid taking a "slash and burn" approach to health care with "arbitrary" cuts and "poorly considered policies".
Warning the planned overhaul of the NHS could see focus shift from quality to cost, they questioned the value for money of reforms amid public spending cuts.
The proposals, set out in Health Secretary Andrew Lansley's White Paper, are designed to give GPs much of the multimillion-pound budget currently handled by primary care trusts (PCTs) and give hospital trusts greater independence.
But they have already sparked considerable debate, with critics suggesting the changes could destabilise the health service.
Dr Hamish Meldrum, chairman of council of the BMA, said: "There are proposals in the White Paper that doctors can support and want to work with. But there is also much that would be potentially damaging.
"The BMA has consistently argued that clinicians should have more autonomy to shape services for their patients, but pitting them against each other in a market-based system creates waste, bureaucracy and inefficiency."
In its report, the BMA set out a series of concerns, concluding: "There are aspects of the White Paper's proposals which have the potential to undermine the stability and long-term future of the NHS."
Acknowledging the reforms had "positive elements", such as devolving more control to patients and frontline clinicians, it said these were threatened by plans for a market-based approach.
Commenting on the BMA's report, Mr Lansley said: "We need a healthcare system where the management of the care of patients is combined with an understanding of how resources are used. Healthcare professionals are best placed to do this and know where resource is needed to improve outcomes for patients."