The health secretary has called on GPs to adopt longer opening hours in a bid to improve patient access.
Alan Johnson has written to every GP in England asking them to accept government proposals for practices to open in the evening and at weekends.
The British Medical Association (BMA) has been resisting the reforms but ministers have warned they are willing to impose the changes on family doctors.
The government wants practices to open 30 minutes longer a week for every 1,000 patients registered - equating to an additional three hours for an average GP practice.
In return the government will provide an additional 1.5 per cent increase in investment for primary care work, amounting to £100 million a year or £12,000 per practice.
Mr Johnson wrote: "We believe that a guaranteed 1.5 per cent increase in practice income, combined with an additional 30 minutes opening per week for every 1,000 patients, represents a balanced offer that both increases investment in primary care and provides a better service for patients."
The General Practitioners Committee (GPC) rejected the government's original proposals before Christmas. Mr Johnson said he was "disappointed" at the GPC's stance and called on individual GPs to back the reforms.
Alternative proposals have now been put to the GPC, allowing greater flexibility for primary care trusts to work locally with GP practices.
Mr Johnson said: "We want to continue to work with the profession and wider stakeholders, not only to improve access to GP services but also to support wider improvements in primary care.
"We are developing a wide-ranging strategy for primary and community care that is looking at how to develop services in ways that focus ever more strongly on promoting health, preventing illness and managing long term conditions."
Critics have raised concerns the reforms will penalise patients that wish to see doctors during the day, as well as place an unacceptable burden on family doctors.
Laurence Buckman, chairman of the BMA's GPs committee, told the BBC: "We think this argument over a few hours either way is really a softening up.
"Patients are being prepared to view their GP as not very good and not very willing and not very flexible, and as a result to look kindly on the government's currently favoured model which is that patients should receive general practice from polyclinics."
Mr Johnson said he was "disappointed" by any suggestion longer opening hours would damage care for older people or those with heart disease.
The government is committed to improving access to GP services after "significant numbers" of patients said the NHS needs to offer a greater choice of appointment times, faster access to doctors and the ability to book advance appointments.
To incentivise GPs, Mr Johnson confirmed today the Department of Health will reward practices that report high level of patient satisfaction on the ability to make advance appointments and to see a GP within two working days.