The government's drive to push care out of hospitals and into new polyclinics is flawed, an expert has said.
Health bosses have been asked to set up polyclinics
After studying pilot schemes, Professor Martin Roland, of Manchester University, said focusing GP care in polyclinics would harm patient choice.
Polyclinics are effectively super-surgeries, housing GPs alongside other services such as hospital care, physiotherapists and social services.
But the government said polyclinics would not be forced on authorities.
Health Minister Lord Darzi said: "We are not imposing polyclinics on anyone.
"The 150 health centres announced in the NHS Next Stage Review Interim Report are additional, new capacity, and we have not suggested merging small practices.
He said it would be up to primary care trusts to decide what was best for the communities they served.
Lord Darzi added: "People want healthcare that is more personalised and convenient...This is about the local NHS making changes that suit people's needs: clinically led, locally driven and putting the public first."
Ministers envisage relatively minor hospital treatment, such as dermatology, minor surgery and diabetes care will be increasingly done in these centres.
But professor Roland said there were concerns over the quality of care provided by the super-surgeries, and that moving services out of hospitals was inefficient.
He said that after carrying out an analysis of 30 demonstration sites being used to pave the way for the changes, he had serious concerns.
He said the current model of GP practices provided more choice and better access than polyclinics.
And while standards could vary widely, overall they were judged to provide better care than polyclinics, he said.
There are no mandatory training standards set out for the doctors and nurses taking on extra responsibilities in the polyclinics.
Professor Roland, director of the university's National Primary Care Research and Development Centre, also said there were concerns about hospital consultants running clinics in the community.
He said last time it was tried in the 1990s doctors did less work because of the increased amount of travelling and lack of access to resources such as blood testing labs and scanners.
Professor Roland, who has written for the British Medical Journal on the subject, said: "Primary care trusts have already been told to start setting up polyclinics, but I think the government has to rethink its approach."
He said the current funding system discouraged hospitals and GPs from working together because hospitals were only paid per patient treated and so had no interest in keeping patients in the community.
Last week the British Medical Association said polyclinics were being forced on to the NHS even when there was no need for them.