A "significant level" of social distancing will be needed for many months until a vaccine is found for coronavirus, a UK Government adviser has suggested, as ministers are expected to announce a three-week extension to the lockdown this afternoon.

Leading epidemiologist Professor Neil Ferguson from Imperial College London, said as restrictions were eased, more testing would be needed to isolate individual cases and trace their contacts to keep future outbreaks under control.

"Because without that, our estimates show we have relatively little leeway. If we relax measures too much then we'll see a resurgence of transmission.

"What we really need is the ability to put something in their place. If we want to open schools, let people get back to work, then we need to keep transmission down in another manner.”

He then stressed: “I should say, it's not going to be going back to normal. We will have to maintain some form of social distancing, a significant level of social distancing, probably indefinitely until we have a vaccine available."

It is thought that, despite efforts to accelerate the creation of a viable vaccine, this will take several months to realise at the earliest.

Prof Ferguson’s comments came as Nadine Dorries, the UK Health Minister, took to Twitter to urge journalists to stop asking about an exit strategy.

She said: "There is only one way we can 'exit' full lockdown and that is when we have a vaccine. Until then, we need to find ways we can adapt society and strike a balance between the health of the nation and our economy."

Matt Hancock, the UK Health Secretary, said he agreed things would not go back to how they were, at least in the short term.

He stressed the number of deaths was still "far too high" for any exit strategy to be set out, adding the public must instead focus on staying at home.

He told Sky News: "What Nadine was saying is the idea that we'll immediately...switch off all of the measures and return to...things exactly as they were; that is not likely in the short-term."

Speaking on BBC Radio 4's Today programme, Mr Hancock said that how ministers communicated with the public had a "direct impact" on the number of cases and deaths, which were "still far too high".

In a tetchy exchange, he insisted the Government would “not be distracted into confusing that message".

Mr Hancock went on: "The scientists can say what they like, the commentators can say what they like, the interviewers can say what they like. We will do what is best by dealing with this virus."

He said the aim was to "talk about what is needed now and when we need to change that, we will".

Sir Keir Starmer, the Labour leader, has said his party will back an extension to the lockdown but has called on ministers to set out an exit strategy explaining how restrictions will eventually be lifted.

Today’s Cabinet meeting comes after the number of people across the UK, who have died in hospital after testing positive for Covid-19, reached almost 13,000, with growing concern over increasing deaths in care homes.

In a separate development, a leaked letter written on Saturday to a senior official at the Department of Health and Social Care by the Association of Directors of Adult Social Services says mixed messages from the Government have created "confusion and additional workload".

Seen by the BBC, the letter also raises fears about funding, testing, personal protective equipment and the shielding scheme for vulnerable people.

Dominic Raab, the Foreign Secretary, standing in for Prime Minister Boris Johnson as he continues to recuperate from the disease, will chair the Cabinet meeting.

It is expected that ministers will be briefed on the latest situation by Sir Patrick Vallance, the Government’s Chief Scientific Adviser.

Mr Raab will then lead a virtual meeting of the Cobra civil contingencies committee, attended by, among others, Nicola Sturgeon, the First Minister, when it is expected the extension of the lockdown will be formally approved.

The Secretary of State will also this afternoon take part in a "virtual summit" of G7 leaders hosted by Donald Trump, the US President.

Downing Street has made clear Britain will not follow America’s example in cutting funding to the World Health Organisation, saying the body has "an important role to play in leading the global health response".

Meanwhile, the human cost of the epidemic was underlined with the disclosure that the latest victims of the disease included pregnant nurse Mary Agyeiwaa Agyapong, 28, who had worked on a general ward at Luton and Dunstable University Hospital for five years.

Her baby, a girl, was delivered successfully and was doing well, according to the hospital.

Elsewhere, Captain Tom Moore, 99, who has walked 100 lengths of his garden to generate cash for the NHS has been praised as "an inspiration to us all" as his fundraising campaign passed the £12 million mark. He had originally hoped to raise £1,000.