The number of GPs in England has fallen sharply in the past year, despite a government pledge to increase the supply of family doctors by 5,000.

The total number of full-time equivalent GPs working in England dropped by 1,193 in the year to September, figures from NHS Digital show.

The numbers have shrunk despite efforts by the NHS, ministers and GP bodies to persuade existing family doctors to stay in post and to encourage medical graduates to make a career in general practice.

The decrease raises doubts over whether Jeremy Hunt’s pledge to increase GPs by 5,000 by 2020, which was first made in 2015, will be delivered. Labour accused the health secretary of “astonishing failure” on a key NHS target.

Krishna Kasaraneni, a family doctor and British Medical Association spokesman on GP issues, said: “It is clear from these figures that the NHS is falling some way short of its pledge to recruit 5,000 GPs by 2020, with in fact these numbers showing that the workforce has shrunk by more than 1,000 in England.”

GP practices often do not have the staff needed to treat the growing demand from patients for appointments, caused by the growing and ageing population.

The chair of the Royal College of General Practitioners, Helen Stokes-Lampard, said: “GPs across the country will be gravely concerned about these figures. We understand that change takes time, but we desperately need more family doctors and we need them sooner rather than later.”

It is 18 months since Hunt unveiled a package of measures to improve GP services and numbers should be going up by now, not falling, she added.

Jonathan Ashworth, the shadow health secretary, said: “The government promised to get more GPs into the NHS but in fact there are now 1,300 fewer compared to 2015. This is an astonishing failure of a key part of Jeremy Hunt’s plan for the NHS.”

Many more GP surgeries are shutting their doors because the profession’s serious recruitment and retention problems mean they cannot find enough doctors to hire as staff leave. Some practices say they might not accept new patients since they cannot cope with the people they already have.

GPs say the relentless nature of their jobs is also fuelling a trend towards early retirement. GPs’ workloads have risen by 16% over the last seven years but the number of family doctors has not kept pace, Stokes-Lampard said.

This shortage means that, despite surgeries offering more appointments, patients are waiting longer to get one, she said. “There is a limit to what we can do when there simply aren’t enough of us to deliver the care our patients need and deserve.”

NHS England is spending £100m in what some GPs say is a desperate attempt to hire up to 3,000 family doctors from countries overseas, such as India. However, just 38 new doctors arrived from that route in the first six months of 2017.

The official workforce figures from NHS Digital also show that the total number of GPs in work also fell, over the last year, from 41,865 to 41,324 – a drop of 541.

A report last month by the Health Foundation thinktank found that the average number of patients each full-time equivalent GP has on their books rose 3.2% from 2014 to 2015 to stand at 1,679.

GPs have been offered more flexible working arrangements to encourage them not to quit, while newly qualified doctors are being offered “golden hellos” of £20,000 to live in and train as GPs in the mainly poorer areas where there is a shortage of doctors.

NHS England said: “While GP trainee numbers are now at an all-time high, in the meantime there are real pressures from retirements, which can partly, but not completely, be helped by expanding international recruitment.”

The Department of Health refused to say if Hunt still expected the pledge of 5,000 more GPs to be honoured. “We know there are challenges ahead and that change won’t happen overnight but we are committed to the plans we’ve put in place to recruit more GPs,” a spokesman said. “There are more than 3,000 GPs in training, and 500 new medical school places will be available in 2018, with a further 1,000 in 2019.”