Some 250,000 volunteers in good health have been recruited by the Government to help vulnerable people - while an exhibition centre in London will be converted into a new NHS hospital, Matt Hancock has announced.

The Health Secretary said people are needed to assist with the national effort to tackle coronavirus by shopping, delivering medicines and supporting those who are shielding themselves against Covid-19.

He said more than 35,000 extra staff have already joined up to help fight against the virus, including retired doctors and nurses returning to the service and final year students.

Mr Hancock spoke after it was revealed that number of coronavirus dead in the UK had reached 422 - up from 335 the day before and the largest day-on-day increase in the number of deaths since the outbreak began. Northern Ireland later said there had been a further two deaths there.

Mr Hancock also confirmed that a temporary hospital - the NHS Nightingale hospital - would be opening at London’s ExCeL centre.

It will comprise two wards, each of 2,000 people, and has been set up with the help of the military.

Mr Hancock said 11,788 recently retired NHS staff had responded to the call to return to the service, including 2,660 doctors, more than 2,500 pharmacists and other staff and 6,147 nurses.

“I pay tribute to each and every one of those who is returning to the NHS at its hour of need,” Mr Hancock said. Some 5,500 final-year medics and 18,700 final-year student nurses will also “move to the frontline” next week. Mr Hancock’s announcement comes after the Government faced criticism over its policy on workers, with pictures of packed London Tube trains appearing on social media on Tuesday.

In measures announced on Monday, Prime Minister Boris Johnson told people to only go to work if “absolutely necessary”.

But on Tuesday, Mr Hancock said those who cannot work from home, including key workers in the NHS and social care, should go to work “to keep the country running”.

Mr Hancock said construction workers were among those who could continue to work as long as they could remain two metres apart at all times.

But some builders and construction workers have said they feel “angry and unprotected” going to work, while others are under pressure from employers to go in.

Mr Hancock said: “The judgment we have made is that in work, in many instances, the two-metre rule can be applied.

“In my work place, in the House of Commons, you can see it every day.

“Where possible, people should work from home and employers have a duty to ensure that people are more than two metres apart.”

Deputy chief medical officer for England Dr Jenny Harries said individuals should raise concerns “very firmly” with their bosses if they felt unsafe but the Government could not individually cover every workplace and every scenario.

She also said couples not living in separate households could be spreading coronavirus if they continue to see each other, and suggested they could move in together.

In other developments:

- The FTSE 100 index of leading companies jumped 9% on Tuesday - its second biggest ever percentage rise and its highest ever points gain.

- The organisers of the Tokyo 2020 Olympic Games, due to begin at the end of July, agreed to postpone the event for a year.

- For the first time, all the UK’s mobile networks are sending out a Government message to customers with details of the new shutdown.

- Chancellor Rishi Sunak acknowledged it would not be possible to protect every job and save every business, but said the Government was “looking at pace at what support” can be given to the self-employed.

- A British patient became the first person to die with Covid-19 in Cape Verde

Mr Hancock also responded to criticisms about a lack of personal protective equipment (PPE) for frontline staff, saying 7.5 million pieces of PPE including facemasks had been shipped out in the last 24 hours.

A hotline enables NHS and care staff to request PPE if they do not have it, he added.

“If people are working on the front line to look after us, it’s vital that we look after them,” he said.

Earlier, Mr Hancock told MPs hat volunteering “is a legitimate reason to travel.”

He added: “I just want to make it absolutely clear that for people that are volunteering in the response to Covid-19, people who are caring even with unpaid and informal caring responsibilities, then it is OK to go and do that.

“And you should do that, but you should stay more than two metres away from others wherever possible.

“But this has to be a practical instruction because of course we need to care for people.”

Former health secretary, Jeremy Hunt, has raised concerns that the UK “appears to be testing on a daily basis virtually no more people than over a week ago”.

Mr Hancock said the Government had now purchased millions of tests which are arriving in the next days and weeks.

He told MPs that home is now the “front line” in the fight against coronavirus as the death toll in the UK jumped to 424. The number of deaths in England reached 386, Scotland has recorded 16, Wales has recorded 17 and Northern Ireland’s death toll climbed to five.

But Mr Hancock issued a stark warning, saying stricter measures introduced by the Prime Minister on Monday were not advice but rules that must be followed.

He said: “The spread of coronavirus is rapidly accelerating across the world and in the UK.

“Our instruction is simple: stay at home.”

Mr Hancock added: “These measures are not advice, they are rules and will be enforced including by the police, with fines starting at £30 up to unlimited fines for non-compliance.”