The NHS in England has hundreds fewer GPs than this time last year, new figures show.
Leading medics said that GPs across the country would be "gravely concerned" by the figures.
The number of full-time equivalent GPs in England decreased from 34,495 in September 2016 to 33,302 in September 2017, according to figures from NHS Digital.
The data show that the overall number of GPs, or headcount, also reduced from 41,865 to 41,324 during the same period.
Commenting on the figures, Professor Helen Stokes-Lampard, chairwoman of the Royal College of GPs, 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. We had hoped that at this stage of NHS England's GP Forward View being implemented, we would be seeing more progress.
"Workload in general practice has increased by at least 16% over the last seven years, but the number of GPs delivering care to patients has not risen in step.
"Despite GPs and our teams working hard to deliver more and more consultations, patients continue to wait longer for appointments. This paradox is being seen in GP surgeries across the country, every day, while we work to deliver the vast majority of patient consultations across the NHS.
"We will continue to work with NHS England and others to identify where improvements can be made, but we need to start seeing some progress, and fast.
"GPs are the guardians of our healthcare system, but 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."
Dr Krishna Kasaraneni, from the British Medical Association (BMA), added: "The BMA has successfully lobbied the Government to invest more in general practice, with £500 million of recurrent, extra funding guaranteed in talks earlier this year to help alleviate the pressures on overstretched GP services.
"But general practice still faces a stark workforce crisis with too many GPs retiring early and too few entering the profession, leaving many GP practices struggling, despite their best efforts, to provide enough appointments to patients.
"This latest fall in GP numbers demonstrates that the Government needs to work with organisations like the BMA to ensure we have a coherent workforce plan that gives GP services the capacity to meet rising levels of patient demand."
A Department of Health spokeswoman said: "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.
"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.
"We've also outlined more flexible working options so we can retain the expertise of more experienced GPs within primary care."