Ministers have offered Scottish family doctors an extra £16m to help cover the cost of out-of-hours opening but have been accused of "blackmail" after warning GPs they will take an effective pay cut of £6,000 each if they refuse.

The deal is aimed primarily at helping patients whose work makes it difficult for them to get to their GP during normal working hours. Ministers hope the move will also reduce pressure on A&E wards and the telephone service NHS 24.

The British Medical Association in Scotland has been negotiating the deal with Health Minister Nicola Sturgeon and is now putting the terms to individual GPs.

It is likely most GP practices in Scotland, particularly those in towns and cities, will be forced to open their doors at night and weekends as a result.

The move has been welcomed by patients groups and workers, who say it will enable more people to get to the doctor without losing valuable working time.

But many doctors will enter reluctantly into the deal, if they accept it at all, furious at what they consider "blackmail" by politicians.

Last night a British Medical Association insider admitted: "The status quo is not an option. The BMA is in talks about being more flexible and GPs are willing to be flexible. But if GPs don't extend their opening hours they are going to lose money."

Dr Peter Shishodia, medical secretary of the Lothian Local Medical Committee, said: "GPs are being bullied into this. But if they are forced to do it, most will do it.

"However there are a number of concerns, for example the personal safety of a GP working alone in the evening and the matter of having to persuade reception staff to work in the evening and weekends.

"It may also mean there are fewer appointments available during the day. And if patients using the extended hours service need tests, they will have to come back for them to be done on another day because staff and some facilities won't be available."

Alan McDevitt, medical secretary of the Glasgow Local Medical Committee, said: "If we are able to discuss this rationally, I think most GPs would extend their opening hours.

"But many GPs are incensed about the proposal because the government is saying it wants more for the same money, or they will make things worse, which is blackmail. The Government does not care about whether we can offer a good service or whether this is going to do anything useful for people."

Anne Ritchie, a practice manager at an Edinburgh-based surgery said: "GPs will have no choice but to extend their opening hours. The BMA should have dug its heels in to avoid this situation."

GP surgery hours are being extended to meet patient need so that people do not have to take time off work to go to a doctor.

This means the average practice would open for around three extra hours a week, and it would be up to doctors themselves to determine on which days.

The BMA has argued that the move is impractical because the people most likely to need a doctor are the elderly, the unemployed and long-term sick who can easily be seen during the working week.

However it has no choice but to accept the government's proposals because it is committed to "flexible" patient care and has been given no alternative in its contract.

The move also comes amid growing criticism about GP pay. The average salary for a Scottish GP has risen to £90,619 under a new contract that also allowed them to opt out of providing round-the-clock care.

Last night Jean Turner, executive director of the Scotland Patients' Association, said doctors simply had to become more flexible to meet the needs of their patients.

"Illness does not just happen between the hours of nine and five. There are always going to be emergencies. I welcome this proposal because people do need a more flexible service. Extending doctors' hours has got to be good for patients."

Andrew Watson, spokesman for the Federation of Small Businesses, said the move would allow professionals the chance to access health care without affecting their working day.

A spokeswoman for the Scottish Government said it wanted to see GPs providing extended hours.

"A package of £9.5m extra has been identified for this purpose. Government officials wrote to BMA Scotland on January 24 setting out details and they are currently considering this letter," she said.