Almost half of the GP surgeries that began opening in evenings and at weekends to fulfil David Cameron’s pledge of 8am to 8pm seven-day access have cut their hours because so few patients came.

Pulse, the magazine for GPs, has learned that eight of the 18 pilot areas in England given money last year to roll out the scheme have scaled back the hours they operate or stopped offering appointments outside normal working hours altogether.

The findings raise serious doubts about the need for and viability of surgeries routinely offering extended opening hours, especially given the serious shortage of GPs.

The 18 NHS areas were last year given shares of the £50m “prime minister’s challenge fund” to help deliver the high-profile pledge that Cameron first made in October 2013. He said every patient in England would be able to visit a GP in their area from 8am to 8pm every day of the week by 2020.

But in Devon, for example, four surgeries that began opening between 9am and 5pm on Saturday and Sunday are no longer operating at those times, Pulse established.

In Slough, the local GP-led NHS clinical commissioning group has reduced what was originally a 9am to 5pm appointments service on both weekend days to just four hours on each.

Derbyshire has done much the same at its two seven-day GP hubs, and now offers consultations for only three hours on Saturday or Sunday, rather than the 12 hours each day originally provided.

Similarly, the clinical commissioning groups that commission and pay for healthcare on behalf of patients in five north-west London boroughs have cut the opening hours for their seven-day access pilots.

The fact that few patients want to see a GP outside of normal office hours, and especially at weekends, has raised fresh questions about whether extended hours are a good use of NHS resources.

GP organisations said the lack of demand affirmed their reservations that Cameron’s determination to create “the first truly 24/7 NHS” by 2020 was misguided.

Dr Maureen Baker, chair of the Royal College of GPs, said: “It doesn’t surprise me that schemes to extend access to GP services have not been as popular as the government predicted. Seven-day access to their GP surgery will be popular with some patients, but it won’t be popular with others, which is why it is essential that services are tailored to the needs of local populations.

“Access to GP services is extremely important but prioritising weekend and evening access must not come at the expense of access and services during normal hours so that patients end up worse off.

“GPs and our teams are making 370m patient consultations a year – 60m more than we were just five years ago – but over the same period, the GP workforce has remained relatively stagnant.”

While the £50m extra funding was welcome, GPs should be left to decide how they organised their services locally to best benefit patients, she added.

“We question whether it would be a good use of NHS resources for patients to be able to have their ears syringed on a Sunday teatime. We urge government to move away from their preoccupation with offering a seven-day NHS, and instead concentrate on securing our existing general practice service and out-of-hours services, so that we can deliver the care our patients need and deserve, close to home, when they need it,” said Baker.

Nigel Praities, the editor of Pulse, said: “This surely must be a wake-up call for the prime minister. His plan to roll out seven-day access to GPs is floundering, and he must look at diverting the funds to shore up core services instead.”

But the Department of Health dismissed Pulse’s findings as “anecdotal” and part of its negative “agenda” on seven-day GP opening.

“This anecdotal investigation does not contain the full facts”, said a spokeswoman.

“Earlier this year some pilots told us they extended their opening hours further following patient demand and an independent first evaluation of the wave one schemes will be published soon. We know Pulse’s agenda when it comes to seven day services but patients want to see a GP in the evenings and weekends.

“We are committed to making this happen to help keep people well and out of hospital.”