The British Medical Association, the largest doctors' association, said the contract on offer was "less damaging" than an alternative the Government had threatened to impose.

The changes to GPs' opening hours will come into force from April and could mean an average-sized practice opening an extra three hours per week, after ministers demanded that more surgeries were to be open in the evenings and at weekends.

The BMA, which represents two thirds of practising UK doctors, had previously said GPs felt "bullied" by the Government, but had not taken a position on the options available. However, at a meeting of its GPs' committee on Thursday, doctors backed a plan which would make money directly available to surgeries to fund extra opening hours.

The alternative, which the government said it would impose if no agreement was reached, would have allowed primary care trusts to commission GP services from other providers - and take thousands of pounds away from practice budgets. The BMA says it has opted for the "lesser of two evils".

Dr Laurence Buckman, chairman of the BMA's GPs Committee said: "GPs have been put in an impossible position and will have to choose between two unacceptable alternatives.

"We have been asked which of these two is less bad and we have responded to GP demand that we do that. We are not recommending any course of action and GPs are free to come to their own decision on how to vote. This is neither a climb down nor a U-turn, but a recognition that between two bad alternatives, one is worse than the other."

He added: "We believe the impositions as they stand will be unsafe for doctors as they will have to work on their own late at night. Patients also won't get the full range of services. GPs are willing to do extended hours, we put forward our own proposal in December - we just don't think the Government's plans as they stand at the moment will be good for general practice or patient care."

The BMA's GP Committee will still poll GPs in England this month to find out how they feel about the contract.

The Department of Health has said that more than six million patients were unhappy with their surgery opening hours. A spokeswoman said: "This is a good deal for patients. We are pleased the GPC are now backing our proposals and urging GPs to support them."