A Government minister accused GPs of operating "gentleman's agreements" in which they promise not to take other doctors' patients, it was reported today.
Health Minister Ben Bradshaw blamed the GP pay system for including a lump sum which "dampened the incentive" to attract new patients and allowed some practices to survive with a small number of patients, the BBC said.
Currently, basic pay consists of the lump sum in addition to payments per patient.
Mr Bradshaw told the BBC: "There is no doubt there are some areas where gentleman's agreements operate that mitigate against lists being open to new patients and therefore work against real patient choice."
He warned that the current system was working against Government plans to encourage patient choice as a way of fostering competition and driving up standards in health care.
The British Medical Association denied the existence of gentleman's agreements.
Laurence Buckman, chairman of the BMA's GPs committee, told the BBC: "It is absolute nonsense to suggest there are gentleman's agreements - it just doesn't happen.
"Nor are we going to compete for patients, that is not the way general practice works."
Mr Bradshaw's comments came ahead of today's publication of the Government's strategy for primary and community care.
The strategy builds on Lord Darzi's review of the NHS.
The report, published on Monday, outlined measures to raise standards of care and give patients more choice in how and where they are treated.