A set of briefing slides used by the British Medical Association (BMA) in its consultation with doctors shows they may feel they have no option but to leave the NHS.

The BMA insisted the slides, reported in Pulse magazine, did not represent the union asking doctors to quit.

A spokeswoman said they detailed the "consequences and risks" of all the options open to GPs.

One slide said the use of private providers was not yet large enough to replace the role of family doctors. But it said: "It can be argued that the Government's clear agenda, to introduce alternative providers, will result in GPs being faced either with accepting far worse terms of employment or of leaving the NHS entirely.

"The Government is clearly building up a "stockpile" of medical manpower. At present, it does not have sufficient to replace GPs were they all to resign. Nor is APMS (Alternative Provider Medical Services) ready to fill the gap. Neither of these two statements will necessarily be true in future. In other words, there are real advantages in the profession threatening to leave now, as we currently have far more leverage than we may have in future.

"This would be a huge step. All current income streams would be lost, and GPs would have to face a much more uncertain financial future."

The slide said there would be "huge political impact" from such a move. But it said private GPs could charge patients between £20 and £25 per consultation, with additional fees for other work. "The Government would seek to portray us as the wreckers of the NHS," it said.

"We would have to work hard to show that we had been left with no choice. This could potentially have catastrophic or terminal effects on the Government. However, there would also be benefits. The profession would escape from constant political interference and the setting of politically-motivated targets."

The Government is embroiled in a row with doctors over extended opening hours for GP surgeries. It wants surgeries to open for an extra half an hour for every 1,000 patients, in blocks of one and a half hours. For an average GP practice with 6,000 patients, this would mean an extra three hours a week.