GP surgeries face a "catastrophic meltdown" because of changes to the way NHS money is allocated, leading family doctors have warned.
The Royal College of General Practitioners (RCGP) told The Times it has been inundated with calls from surgeries struggling to pay their bills since changes to funding were introduced in April.
It claims 98 GP practices across the UK are at risk of imminent closure and called on the Government for an emergency £15 million bailout.
As well as leaving 700,000 patients without a family doctor, the knock-on effect would also cause delays for millions of patients at other surgeries, it warned.
The Government last month begun phasing out a funding arrangement called the Minimum Practice Income Guarantee (MPIG) over a seven-year period.
MPIG means many smaller GP practices are guaranteed a minimum level of funding that is not dependent on the number of patients on their practice list.
In a letter printed in the newspaper, Professor Nigel Mathers, honorary secretary of the RCGP, said: "General practice is on the verge of a catastrophic meltdown, with nearly 100 GP practices facing closure within months due to the phasing out of the (MPIG) .
"So grave is the threat to patient care in places such as Essex, Leicester, Sheffield, Cumbria and east London, the RCGP is calling for an emergency fund to help the practices affected.
"In due course 1,700 practices could be affected by the changes with the care of 12.2 million patients under serious threat."
It added that funding for general practice has "fallen to an all time low".
Earlier this year NHS England published an anonymised list of 98 'outlier' practices that could lose more than £3 per patient per year.
Some practices on the list will lose more than £100 per patient per year while others stand to lose around £20 or £30 per patient.
The BMA had warned that large areas of rural England could be left with no GP practice, b ut NHS England denied phasing out MPIG will have a disproportionate impact village practices.