People in the South West are having to wait the longest for ambulances to respond to the most serious calls, new data from NHS England shows.
The average ambulance response time in December dealing with the most urgent incidents was nine minutes and 13 seconds across all of England.
The most urgent incidents are defined as calls from people with life-threatening illnesses or injuries.
The South West had the longest time at 11 minutes 38 seconds compared to London's, which had the fastest at seven minutes and nine seconds.
The nine minutes and 13 seconds average was the second-highest since current records began in 2017.
The highest ever was recorded in October with nine minutes and 20 seconds.
The average response time to less urgent calls like burns, epilepsy and strokes was 53 minutes and 21 seconds - the second-longest time on record.
For these second rank response times, the South West again had the slowest times at an average of one hour 13 minutes and 16 seconds, compared to 33 minutes and 29 seconds in the South East, which had the fastest.
Watch: Inside 'overloaded' Barnet Hospital where ambulances wait hours to drop off patients
Ambulance services in England are continuing to struggle with near-record long response times and handover delays at A&E departments, new figures show.
Response times for urgent calls – such as late stages of labour, non-severe burns and diabetes – averaged two hours, 51 minutes and eight seconds, again the second-longest time on record.
NHS England, which published the figures, said staff had dealt with the highest ever number of life-threatening call-outs last month, averaging one every 33 seconds.
It also said on average more than 66,000 NHS staff at hospital trusts were off work each day in December.
Absences related to COVID-19, including people who were self-isolating, climbed from 12,508 on 1 December to 40,149 on 31 December.
Meanwhile, nearly one in four patients arriving at hospitals in England by ambulance last week waited at least 30 minutes to be handed over to A&E departments.
Some 18,307 delays of half an hour or more were recorded across all hospital trusts in the seven days to 9 January, NHS England data shows.
This was 23% of all arrivals by ambulance, the same proportion as the previous week and matching the level seen at the start of December.
The figure had dropped as low as 13% in the week ending 26 December.
A handover delay does not always mean a patient has waited in an ambulance. They may have been moved into an A&E department, but there were no staff available to complete the handover.
Responding to the figures, NHS national medical director Professor Stephen Powis said: “Omicron has increased the number of people in hospital with COVID at the same time as drastically reducing the number of staff who are able to work.
“Despite this, once again, NHS staff pulled out all the stops to keep services going for patients – there have been record numbers of life-threatening ambulance call outs, we have vaccinated thousands of people each day and that is on top of delivering routine care and continuing to recover the backlog.
“But staff aren’t machines and with the number of COVID absences almost doubling over the last fortnight and frontline NHS colleagues determined to get back to providing even more routine treatments, it is vital that the public plays their part to help the NHS by getting your booster vaccine, if you haven’t already.”