The findings came as GPs and other NHS staff reacted furiously to health secretary Jeremy Hunt's threats to impose a seven-day contract on NHS consultants. Many NHS staff working over the weekend used the #ImatworkJeremy hashtag to make the point that the health service already operates seven days a week.
Meanwhile, an online petition calling on MPs to debate a vote of no confidence in health secretary Jeremy Hunt over his seven-day NHS proposals has secured more than 150,000 signatures within a matter of days. Parliament is required to consider a debate on any petition that gains over 100,000 signatures.
The GPonline poll found that of 477 GPs who took part, 20% work in out-of-hours NHS services.
Many GPs also report having no choice but to carry out administrative work over weekends and during evenings because of soaring practice workload. Jubilee Street practice GP and MPIG campaigner Dr Naomi Beer said on Twitter:
A report by the National Audit Office last year said around 10% of GP practices retained 24-hour responsibility after the 2004 GP contract deal.