NHS accident and emergency departments in England recorded their worst-ever performance in December.
The latest figures show 79.8% of patients were seen within four hours in all A&E departments last month, compared with 81.4% in November 2019 and 86.5% in December 2018.
It comes as pressure on the health service continue to grow.
The NHS experienced its busiest month on record in December 2019, with an unprecedented number of A&E attendances and ambulance call-outs.
The health service's monthly performance statistics show there were 2,181,024 attendances in December - a 6.5% rise from the same time the previous year.
This resulted in 4,307 extra attendances per day, the highest number on record.
The amount of people attending emergency departments throughout 2019 was up almost 5% on 2018 and rose 14.2% in three years, according to NHS England.
There were 560,801 emergency admissions in December, 2.9% higher than the same month last year.
Ambulances attended 790,294 call-outs in December, which also made it the busiest month on record.
The number represents a 5.3% increase on the same month in 2018.
Some 10,000 of these call-outs were to the most serious, life-threatening cases, and is again the highest number recorded in a month.
It represents a rise of 16.6% from the previous year.
There were 1.2 million more attendances at A&Es overall in 2019 than in 2018 - a 4.8% rise.
The figures also show almost 100,000 patients had to wait more than four hours for a bed in December.
Some 98,452 patients waited more than four hours to be admitted, which is 64.6% higher than December 2018.
There were 4.6 million people on the waiting list to start treatment as of the end of November 2019, up from 4.4 million.
Professor Stephen Powis, NHS medical director, said: "A&Es across the country are currently very busy - in 2019 we treated over a million more patients in our A&Es than the previous year.
"We have got more hospital beds open than last winter, but flu has come early and is around twice as high as this time last year.
"For the public there is still time to get your flu jab, and remember to use the free NHS 111 phone and online service and your local pharmacist.
"The continued increase in people's need for care underlines the need for more beds and staff across hospital and community services, which is why the Government's commitment to increase the number of nurses by 50,000 and invest in new and expanded facilities will be crucial over the coming years."