People should avoid calling 999 unless it is an emergency because ambulance services and A&E departments are struggling to cope with the winter illness season, an NHS chief has said.
Peter Bradley, the national director of ambulance services, said the entire health system was "struggling to cope".
Mr Bradley, who is also chief executive of the London Ambulance Service, told today's Daily Telegraph ambulance services in England had just had their busiest week ever.
He put it down to the coldest start to a winter for 30 years causing a sharp increase in falls and breathing problems combined with outbreaks of flu and the winter vomiting bug norovirus.
Mr Bradley warned things would get worse with a rise in drink-related accidents over Christmas and New Year adding to the problem.
He said: "It has been the most difficult 10 days I have seen in the last 10 years. It is absolutely horrendous.
"Hospitals are full and A&E departments are struggling. We have ambulances having to wait longer to offload patients and that is causing difficulties.
"The message is that the public really needs to do their best to avoid using A&E and ambulance services unless it is a genuine emergency. Use walk-in centres, NHS Direct and pharmacies because the relentless increase in activity will not ease for the next few weeks."
Calls to the ambulance service normally hit a peak over Christmas and New Year as the party season coincides with a rise in illness and health workers' holidays.
Mr Bradley said some areas had seen a 30 per cent rise in calls over the past 10 days.
Ambulance workers are being offered bonuses of between £300 and £800 for doing a month's worth of overtime in a bid to meet demand.
Other measures that have been taken include suspending meal breaks and drafting in private ambulance companies and the volunteer St John Ambulance service to help in some areas.