Figures suggest paramedics are unable to respond to 100,000 urgent 999 calls each month because they are stuck outside hospitals waiting to hand over patients.
Health charities warn delays are putting thousands of lives at risk, with heart attack and stroke victims among those waiting too long for teams to arrive.
National guidance says that patients arriving at A&E by ambulance should be transferred to the care of hospital staff within 15 minutes.
But data from NHS England shows that more than four in ten (42.2 per cent) of those arrivals last week waited at least 30 minutes, the highest figure so far this winter.
1,313,218 work cycles were lost last year as a direct result of delays in ambulance delivery, according to an analysis of NHS data by The Guardian and the Association of Ambulance Chief Executives (AACE).
Doctors said the figures – equivalent to 3,500 a day – are “staggering” and called on ministers to take immediate action to tackle the problem.
Anna Parry, chief executive of AACE, which represents the heads of NHS England’s 10 regional ambulance services, warned: “Lost duty cycles have a profound impact on the resources available to local ambulance services.”
The “most detrimental impact” is on 999 patients with life-threatening illnesses “who need us most,” he added. The crisis is being caused by increasing demand for emergency care, staff shortages and a lack of social care beds.
More than four in ten (42.2 percent) ambulance arrivals last week waited at least 30 minutes – the highest figure so far this winter – double the 15 minutes stipulated in national guidelines (photo by archive)
1,313,218 work cycles were lost last year as a direct result of delays in ambulance delivery (file photo)
This means hospitals cannot discharge patients who are medically fit to leave, so they struggle to find space for new arrivals waiting in ambulances outside.
Dr Sonya Babu-Narayan, clinical director at the British Heart Foundation, said: “This inevitably has a domino effect where ambulance staff caring for patients in hospital are unable to attend the next call.”
“This desperate situation becomes even more pressing as the NHS grapples with the enormous challenges it faces this winter.”
Every minute that passes when someone has had a heart attack or stroke they risk further damage and even death, he added.
She said: “No patient and their family should have to endure dramatic delays, and it is a tragedy to see this happen on such a large scale.”
There have been reports of ambulances queuing 18 people long outside the hospital, some teams waiting eight hours to drop off a single patient and pensioners left all night on the floor of their homes waiting for an ambulance after suffering a fall.
NHS England said delivery delays had improved ahead of winter, but accepted there was “clearly still a lot of work to be done” to reduce “unacceptably long waits for patients” in some parts of the country. It is “prioritizing the sickest patients,” a spokesperson added. .