Tony Blair yesterday admitted that government targets in the health service had been "too crude" and risked over-burdening medical staff.

The prime minister was accused of being "out of touch" after he expressed astonishment that some family doctors are refusing to book appointments more than 48 hours ahead in order to hit a government target.

Challenged repeatedly over the issue by members of the audience on the BBC's Question Time on Thursday night, he said such an outcome was "absurd".

Mr Blair scrambled to regain the initiative by conceding that targets needed to be made "sufficiently flexible" and should not "overburden the system".

Angela Coulter, chief executive of the Picker Institute that monitors patients' experiences of the National Health Service, said the issue was "a really significant problem".

The institute's regular surveys show that patients are less, rather than more, satisfied with GP waiting times.

John Reid, the health secretary, acknowledged that there were problems but stressed that the target had produced much quicker access for many patients. A few years ago, many patients had to wait a week to 10 days to see a GP, he said, while on the latest figures, 97 per cent are seen within two days.

The target guidance makes clear that patients should be able to book appointments further in advance. But last November, health department surveys showed more than 12 per cent of practices were ignoring that and making patients book within the 48 hours - a proportion the department says has now fallen below 2 per cent.

Ministers are looking at altering the GPs' contract so it rewards those who see the highest proportion of patients on the day they want to be seen, Mr Reid said.

Andrew Lansley, the Conservative health spokesman, said Mr Blair's comments "show just how out of touch he is". The target was not making it easier to a see a doctor. On the contrary, it was "reducing a GP's flexibility to manage patient demand".

Dr Hamish Meldrum, chairman of the British Medical Association's GP committee, said the target was a crude one that distorted priorities.

But Dr John Oldham, head of the health department's team that has been helping GP practices hit the 48-hour target, said it was perfectly possible for almost all practices to do so and offer booked appointments further out, simply by matching demand to available appointments better.

"In a small minority of cases capacity is an issue, but even there it can be achieved by using nurses for some appointments and offering telephone or e-mail consultations," he said.