Figures from the UK Health Security Agency show that the rate of flu admissions was 6.8 per 100,000 people in the week to 11 December, compared to 6.6 per 100,000 for COVID-19.

This also means that flu admissions are running at a higher rate than in any week during the past four winters - something that will worry health workers, who are already under pressure.

Dr Conall Watson, UKHSA consultant epidemiologist, said: "Flu is now circulating widely and we have seen a sharp rise in the rate of hospitalisations for flu this week, particularly among the under-fives and over-85s.

"Admissions are now at the highest point since the 2017/18 season and we are expecting case numbers to continue increasing as we move further into winter.

"The flu vaccine offers the best protection against severe illness and it's not too late for everyone eligible to get it.

"Uptake is particularly low in those aged two and three, so if your child is eligible please take up the offer."

The admission levels for flu and COVID-19 are both rising but the rate of flu admissions has risen more sharply - nearly doubling from 3.9 per 100,000.

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Admissions are highest among those aged 85 and over (23.1 per 100,000 people - up week-on-week from 10.7).

There has also been a rise in the rate among children aged four and under - from 8.4 to 20.7.

All children aged two and three are eligible for a flu nasal spray vaccine at their GP surgery but only 37.4% of two-year-olds and 39.5% of three-year-olds have taken up the offer.

Some 33 million people in England can get a free flu jab this year, including those aged 50 and over, primary school-aged children, and some secondary school-aged children.

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Other groups eligible include pregnant women, people in care homes, frontline health and social care staff, carers, those aged six to 49 with a specified health condition, and household contacts of people with weakened immune systems.

On Thursday, NHS figures were published showing that an average of 1,162 flu patients were in England's hospital beds each day last week - up 63% from 712 the previous week.

Some 87 flu patients were in critical care beds - up 45% week-on-week.

In the equivalent period last winter, just 25 patients a day were in hospital with flu and only one was in critical care.