Around 89% of doctors think that more competition in the health service brought on by government reforms to the NHS will cause services to become fragmented, a survey has revealed.
The poll of British Medical Association (BMA) members also found that 65% think making NHS providers compete with private companies will lead to a lack of patient care, while 61% believe treatment time given to patients will reduce as a result of the changes.
Some 66% said health inequalities would become larger when the responsibility for commissioning services is handed over to GPs.
Only one in five think that an increased amount of competition will help to drive up standards and boost the quality of care provided by the NHS.
Some 67% think closer working between GPs and hospitals would improve services for patients, but only 34% have faith the reforms will lead to this.
The Health and Social Care Bill, currently going through parliament, will see £80bn of the NHS budget handed to GPs, enabling them to commission services.
The poll found 33% are broadly opposed to the reforms, 18% are broadly supportive, and 36% are waiting to see what happens.
BMA Chairman Dr Hamish Meldrum said: "This survey shows that the government can no longer claim widespread support among doctors as justification for these flawed policies.
"While there are widely differing opinions, with many still to decide, there are a number of key issues where the majority have very clear concerns."