Doctors have voiced their opposition to polyclinics
Up to a fifth of England's GP surgeries are under threat of closure, the Conservative party is claiming.
The Tories said their research suggested 1,700 would shut down under plans for new "polyclinics", housing doctors alongside other medical staff.
In a speech to the King's Fund, leader David Cameron accused Labour of "trying to abolish the family doctor".
Heath Secretary Alan Johnson has said Mr Cameron is "misleading the public", insisting GP services will not be cut.
Polyclinics are designed to offer a range of care services by social workers, nurses, physiotherapists and doctors.
In particular, the government wants to see them provide services traditionally carried out in hospitals, such as diabetes treatment, minor surgery and diagnostic tests.
The government has called for 150 polyclinics to be set up, seeing them as the future of an NHS where hospitals will concentrate only on the most complicated care.
Doctors and patients' groups have condemned the policy, but the NHS Confederation said they had the potential to improve care.
The Tory estimates are based on the average number of GPs per practice in each primary care trust, and assume every polyclinic will be staffed by 25 GPs.
There are currently 8,261 GP practices in England, of which 1,546 are in London.
According to the party, 1,091 could close in London, and 609 in the rest of the country.
In his speech to the King's Fund, Mr Cameron said: "Labour has already tried to bring about the end of the district general hospital. Now they are trying to abolish the family doctor service.
"Communities which have lost their Post Office, their local shops and their local police station, are now going to lose their doctor.
"Of course there are circumstances where GPs coming together in larger practices or larger premises, and offering new services, are entirely welcome.
"What I object to is the government's policy of imposing polyclinics on local communities without public support and in the face of opposition from doctors."
But Mr Johnson said Mr Cameron had exposed his party as opponents of NHS investment.
"We are opening 150 new GP-run health centres, open from 0800 to 2000, seven days a week," the health secretary said.
"Because this programme is all paid for with new money, none of it will lead to a reduction in traditional GP services."
Lord Victor Adebowale, chief executive of Turning Point, which provides care to people with complex addiction and mental health problems, said: "It is simplistic to say that polyclinics are either the way forward or that they signal the end of local GP provision.
"We have consistently welcomed the idea of polyclinics, but only if they are designed to provide a new kind of service that is accessible to everyone and is better suited to meeting the needs of local people."