Tens of thousands of people across England could be left without a local GP practice, doctors' leaders have warned.
The British Medical Association (BMA) said that almost 300 GP surgeries are facing closure - which could lead to thousands of patients looking for a new family doctor.
A new BMA poll of more than 2,800 GP surgeries - around a third of practices around England - found that 10% (294) believe they are financially "unsustainable".
More than 900 GP practices believe they are in a "weak" financial position, with only 5% reporting their finances were in a "strong" state, the survey found.
The BMA said that the figures show that the "crisis in general practice is set to worsen" as it called on the Government to safeguard GP services for patients.
Figures from the poll also reveal that many GPs are planning to retire or move abroad. Almost half of practices (46%) said they were expecting some of their doctors to leave for these reasons.
"This survey provides further evidence of the state of emergency facing general practice," said BMA GP committee chair Dr Chaand Nagpaul.
"Almost half of GP practices are looking at the loss of part of their workforce at a time when there is a shortfall in new doctors entering general practice. As GP services struggle to replace existing staff who leave, it will inevitably make it more difficult to maintain current services to patients and particularly to offer enough appointments for them.
"Just as worrying, close to 300 practices looking after tens of thousands of patients believe their financial future is unsustainable.
"GP practices are facing this dire situation because they are being overwhelmed by rising patient demand, cuts to funding, staff shortages and more unfunded work being moved from hospitals into the community. Given these pressures it is unsurprising that GPs are considering leaving the NHS while new medical graduates are turning their backs on a career as a GP, a situation undoubtedly worsened by the Government's appalling handling of the junior doctor contract.
"With hundreds of GP practices facing financial uncertainty, and close to 300 facing possible closure, we need the government to act urgently to deliver a comprehensive rescue package that safeguards GP services for patients. We cannot have a situation where thousands of patients are left without a local GP practice that can deliver the care they deserve."
The BMA has launched a new initiative aimed at providing GP surgeries with support and is sending a package of materials to every practice across England.
A Department of Health spokeswoman said: "We know GPs are under pressure and that is why we have agreed record investment for general practice.
"We saw an increase in the number of GPs recruited last year, and we will continue to boost numbers with an extra 5,000 doctors in general practice by 2020 - helping to deliver a safer NHS for patients seven days a week."