British soldiers are to begin deploying in London to support the NHS amid growing staff shortages due to Covid-19, the Ministry of Defence (MoD) has said.

Around 200 armed forces personnel are being made available to hospitals across the city, which has been the epicentre of the Omicron outbreak with a huge upsurge in cases.

The announcement comes after Prime Minister Boris Johnson said this week that ministers hoped to "ride out" the latest wave without the need for further restrictions in England.

The MoD said the deployment included 40 military medics and 160 general duty personnel to help fill gaps caused by absences of NHS staff unable to work because they were ill or having to self-isolate.

They will be deployed in 40 teams of five - comprising one medic and four support personnel - and will be targeted at areas where the need is greatest.

It is expected they will be "on task" for the next three weeks.

In addition, 32 military co-responders are being provided to support the South Central Ambulance Service, working alongside paramedics until the end of March.

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The Royal College of Nursing's director for England, Patricia Marquis, said the deployment meant the government could no longer deny there was a "staffing crisis" in the NHS.

"The Prime Minister and others can no longer be dismissive of questions about the ability of NHS staff to deliver safe care," she said.

"Once the military has been brought in, where does the government turn next in a bid to 'ride out' the wave rather than deal with it?"

Around 1,800 service personnel are already deployed across the UK to support the civil authorities in their response to the pandemic.

They include 313 personnel assisting the Welsh Ambulance Service NHS Trust and 96 with the Scottish Ambulance Service, while more than 1,000 are helping the vaccine booster programme.

The announcement comes as the PA news agency understands that as of yesterday, 17 hospital trusts in England had declared critical incidents - an alert to signal that there are fears priority services cannot be safely delivered.

Government figures showed there were 17,988 people in hospital in the UK with Covid-19 as of 5 January, up 50% week-on-week and the highest total since 18 February.

Infections remain high, with the latest official figures showing there were a further 179,756 lab-confirmed cases of the virus recorded in the UK as of 9am yesterday.

'Extraordinary increase' in number of UK cases

Meanwhile, the Head of the School of Life Sciences at the University of Nottingham said there has been an "extraordinary increase" in the number of cases in the UK.

Speaking on RTÉ's News at One, microbiologist Professor James McInerney said they have "reached saturation" in their ability to test.

He said the Office for National Statistics has estimated that last week as many as four-million people in the UK were positive.

However, Prof McInerney said that while more people are being admitted to hospital, the length of time they are staying there seems to be shorter.

"We estimate that the number of cases maybe as much as ten times bigger than it was in January of last year, the number of people on mechanical ventilation is about a quarter," he said.

"So that's a big difference, and it's stayed flat for the last number of weeks."

Prof McInerney said the Omicron wave is still at a high level in Britain and the NHS is under severe pressure.

He said vaccination is "unquestionably" having a huge effect on serious disease.