There are now more Covid-19 patients in NHS hospitals in England than during the peak of the first wave in April, new figures reveal.

NHS England data shows there were 20,426 patients in NHS hospitals in England as of 8am on Monday, compared to the 18,974 patients recorded on April 12.

Dr Yvonne Doyle, medical director at Public Health England, said: “This very high level of infection is of growing concern at a time when our hospitals are at their most vulnerable, with new admissions rising in many regions.”

The figures come amid warnings that hospitals in the South are facing a rise in pressure due to the increasing number of coronavirus patients.

Saffron Cordery, deputy chief executive of NHS Providers, said: “We know that the rate of Covid-19 admissions is rising and some trusts are reporting up to three times the number of Covid patients than at the peak of the first wave.

“This means hospitals and also ambulance services in Tier 4 areas and beyond are incredibly busy, compounded by increasing staff absences due to illness and the need to self-isolate.”

Dr Nick Scriven, immediate past president of the Society for Acute Medicine, called the trend “extremely worrying” and said “systems will again be stretched to the limit”.

“It is not ‘just the case’ of using the Nightingale hospital as there are simply no staff for them to run as they were originally intended (mini intensive care units),” he said.

“They could play a role perhaps if used as rehabilitation units for those recovering but, again, where do we find the specialist staff – the NHS simply does not have the capacity to spare anyone.”

Paramedics in the capital are receiving support from other ambulance services in the South as they receive up to 8,000 999 calls each day.

London Ambulance Service described Boxing Day as one its “busiest ever days”, with 7,918 callouts – up more than 2,500 on the 5,217 received on the same day last year.

Medics remained busier than usual on Sunday, with 7,111 calls, compared with 5,411 on December 27 2019.

The South Central Ambulance Service (SCAS) said it is “prewarning” the military and fire service that paramedics may need help after an average increase of 10% in 999 calls over the Christmas period and a threefold increase in 111 calls, along with a 60-70% increase in absence rates with staff symptomatic or self-isolating.

Dr Katherine Henderson, the president of the Royal College of Emergency Medicine, described her experience of working in a hospital on Christmas Day as one of “wall-to-wall Covid”.

She told BBC Breakfast: “The chances are that we will cope but we cope at a cost – the cost is not doing what we had hoped, which is being able to keep non-Covid activities going.

“So we will stretch staff, the problem is at the moment we have a lot of staff sickness.”

Professor Jackie Taylor, president of the Royal College of Physicians and Surgeons of Glasgow, told the programme London and the South East are now experiencing what Scotland went through in the autumn.

The number of further lab-confirmed cases of coronavirus recorded in a single day in the UK also hit a new high of 41,385 as of 9am Monday, according to Government figures.

The Government said a further 357 people have died within 28 days of testing positive for Covid-19 as of Monday, bringing the UK total to 71,109.