The statistics concern Surrey and Sussex Healthcare NHS Trust as part of a special series which highlights the winter pressures facing the health service.
The figures show that in December, 414 of the trust’s patients had to spend between half an hour and an hour waiting in an ambulance at hospital, before they could be transferred to the emergency department.
According to the figures, of that 414, 106 were stuck in ambulances for more than 60 minutes despite NHS England’s target time of up to 15 minutes.
The waits, known as handover delays, can be due to ambulance queues or slow processing at hospitals, and can have the knock-on effect of delaying paramedics being despatched to future emergencies.
In total, 20 per cent of all patients arriving by ambulances at hospital were delayed by between 30 and 60 minutes, according to the figures.
In the week from Christmas to New Year’s Eve, NHS figures showed there were 103 delays of between 30 and 60 minutes, and ten incidents where patients were waiting for more than an hour.
The worst day for delays was Friday, December 29, with 27 patients stranded in ambulances for between 30 and 60 minutes, the figures showed.
The Department of Health said ambulance crews should be able to hand patients over to A&E staff within the 15-minute target time.
It said not doing so increases the risk to patients due to delays in diagnosis and treatment, as well as the chance that a patient will get worse while waiting on a trolley.
The figures are likely to cause concern as doctors and hospital leaders have claimed the current NHS winter crisis is the worst in decades.
Emergency medicine consultant Dr Adrian Boyle, chairman for quality at the Royal College of Emergency Medicine, told Press Association: “Everybody is struggling at the moment.
“Every type one emergency department that I know of is under serious and sustained pressure.
“It feels worse than the equivalent period last year.
“This means that ambulances are waiting outside emergency departments waiting to offload, the emergency departments are full, clinical staff are working extremely hard to try and look after these patients, often having to treat patients in corridors, people suffering lengthy delays.
“And we know that excessive crowding within emergency departments is associated with avoidable deaths.”
Health Secretary Jeremy Hunt apologised to patients for the wave of cancellations, saying it was ‘absolutely not what I want’.