At least three hospitals have declared critical incidents due to high demand driven by surging winter viruses and recent . University Hospitals Plymouth NHS trust said more than 300 people had arrived at Derriford Hospital needing emergency care on Monday and 200 had to be admitted.

A spokesperson said: "We are particularly seeing high numbers of older patients with respiratory problems exacerbated by the cold weather. By calling this critical incident, it triggers our system partners to work differently to support us in keeping patients safe.

"Our emergency department is currently very full and if you do not have an emergency or life-threatening condition, you may be redirected to other healthcare services."

Hampshire Hospitals NHS Foundation Trust also declared a critical incident "due to sustained pressures at our Basingstoke and Winchester hospitals". A statement said the hospital was experiencing a high admission rate, high numbers of patients with infectious diseases requiring isolation, and a low discharge rate.

Julie Dawes, chief nurse for Hampshire Hospitals, said: "This year has seen an unusually high level of winter viruses with a significant number of patients presenting with respiratory issues."

The trust added: "This decision has not been taken lightly; however, beds across both hospitals are full and attendance at our emergency departments is extremely high, which means there is currently no capacity to admit further patients needing our care."

And Royal Liverpool University Hospital declared a critical incident over "exceptionally high" flu cases and urged patients to visit their GPs or call 111 as patients reportedly faced waits of up to 91 hours in A&E.

A spokeperson said the hospital's emergency department was dealing with huge demand "especially with flu and respiratory illnesses, and the number of patients we have taken this action to support the safe care and treatment of our patients, which is our absolute priority".

Visitors were also urged to take measures to curb the spread of winter viruses such as flu and norovirus, such as washing hands and wearing face masks in clinical areas if asked to do so.

Other NHS trusts including NHS Shropshire Telford and Wrekin and Surrey and Sussex NHS Trust declared critical incidents in recent days as winter bites, before standing them down.

NHS figures showed the number of patients in hospital with flu - rising from 1,190 at the end of November to 5,074.

Health chiefs warned infections were "rising at a very concerning rate" and some NHS trusts have experienced the worst Christmas pressures seen for many years.

Professor Julian Redhead, NHS national clinical director for urgent and emergency care, said: "These latest figures show the pressure from flu was nowhere near letting up before we headed into the New Year, skyrocketing to over 5,000 cases a day in hospital as of the end of last week and rising at a very concerning rate.

"On top of flu there is also continual pressure from Covid, while RSV and norovirus hospital cases are also higher than last year, with hospitals putting in place an extra 1,300 beds last week than the same time last year in expectation of this continued pressure from viruses and other demand."

Cases were expected to rise further in the coming days and weeks as a result of festive gatherings where infectious diseases can spread.