Patients are being forced to wait twice as long for an ambulance when their family doctor has called for it, an investigation suggests.
GPs said heart attack victims and those with life-threatening conditions such as sepsis had been left for hours despite clear warnings that they needed emergency assistance.
Freedom of Information disclosures from 10 of the 13 ambulance trusts in the UK show patients waiting far longer when the call came from a GP surgery.
Doctors said critically ill patients had died after long waits for paramedic crews, with GPs left desperately administering emergency oxygen until it ran out.
The British Medical Association (BMA) said it would be raising concerns with NHS England.
Dr Peter Holden, a former negotiator for the BMA’s GP Committee, said: “If I am with a patient who needs an urgent ambulance I have been known to say to the family ‘you dial 999 and deny that I am here’” in order to get a quicker response.
The Association of Ambulance Chief Executives said there was no attempt to deliberately downgrade calls to GP surgeries. A spokesman said some of the figures included calls where GPs had agreed that an immediate response was not required.