Incentives to encourage efficient commissioning among GP consortia could account for up to £800 million of practice income, according to the Health Services Journal.
Citing "senior sources", the HSJ said quality premiums suggested by the government to reward or penalise good commissioning could make up around 10%-15% of income.
According to the government, the premium will be dependent on both quality and financial performance and set under a “commissioning outcomes framework”, although the proportion of indicators that will lie on the financial or quality side remains unclear.
Slamming the reward proposals as "disgracefully unethical", the British Medical Association's Laurence Buckman told the BBC that GP incentive payments could damage trust between doctors and patients.
"We don't understand what the Quality Premium means...It appears that what we might actually be asked to do is to save money and if we save a certain amount of money we will receive some of our pay given back to us. That is something that is appallingly unethical," he said.
However health minister Paul Burstow has denied that the scheme is a mere cost-cutting exercise, telling the media that GPs will be rewarded for improving survival rates and quality of care.
More 'pathfinders' unveiled
Meanwhile, the Department of Health has announced that a second wave of GP pathfinders - tasked with road testing the government's radical new arrangements for commissioning - has now been chosen, bringing the total to 177.
This means that, two years before its planned implementation, GPs covering two-thirds of the country will be operating under the new purchasing arrangements.
The groups will be working together to help manage local budgets and buy services for patients directly with other NHS colleagues and local authorities, the DH noted.
Health secretary Andrew Lansley said the speed of uptake of the new arrangements is "highly encouraging", and "demonstrates significant will on the part of GPs and nurses to get on with designing and purchasing NHS services, so that outcomes can improve for patients”.
However, it seems not all doctors are so enamoured with the direction of travel. A survey by Ipos Mori for the British Medical Association revealed mixed feeling among doctors on the impact of GP-led commissioning.
Two thirds (66%) think it will actually increase health inequalities and 49% feel it will reduce the quality of patient care. And crucially, only 49% responding to the survey agree that GPs will be ready to take on new roles leading commissioning, the BMA said.