Scientists have warned there can be no early easing of lockdown rules, as ministers toughen messaging amid concerns the newer Covid-19 variant may be more fatal than the original virus.

Prime Minister Boris Johnson has urged people to stay home and follow the rules after he revealed the new variant, which emerged in the southeast of England, may cause "a higher degree of mortality".

He and a number of experts have also warned that lifting restrictions too soon would simply lead to another lockdown, leaving the UK with no hope of a return to normality any time soon.

The shift in tone comes as a series of hard-hitting government adverts launched on Friday evening, asking Britons if they "can look coronavirus patients in the eye".

The first of the new adverts, aired on ITV and Channel 4, features COVID-19 patients and the staff looking after them at Basingstoke and North Hampshire Hospital.

It begins with a room full of doctors trying to save someone in intensive care before showing the faces of those very ill with the virus and the medics taking care of them.

They remain silent, staring at the viewer, before a voice asks: "Can you look them in the eyes and tell them you're doing all you can to stop the spread of Covid-19?"

The prime minister's chief scientific officer Sir Patrick Vallance said that with the new variant, 13 or 14 people out of every 1,000 over the age of 60 with the virus are dying.

With the initial virus, the number was 10 in 1,000.

Nurses, meanwhile, have written to the government calling for an "urgent" review into whether standard surgical face masks prevent transmission of the new variant on COVID wards.

Dame Donna Kinnair, chief executive of the Royal College of Nursing has said that some hospitals are using enhanced PPE, creating a "postcode lottery" of protection.

A record 1,820 people were reported to have died of coronavirus on Wednesday, with another 1,401 COVID-related deaths registered on Friday.

The government says that someone is admitted to hospital with the virus every 30 seconds in England, with a quarter of them under the age of 55.

At Friday's briefing, Chief Medical Officer Professor Chris Whitty stressed that infections nationwide are still "at a very high level" and the situation is "extremely precarious".

"The impact of the current wave is still putting significant pressure on hospitals across the country and many patients are very sick," he urged.

"Vaccines give clear hope for the future, but for now we must all continue to play our part in protecting the NHS and saving lives."

Sir Patrick Vallance also cautioned that there is still not enough evidence to tell if current vaccines will protect against the emerging variants from South Africa and Brazil.

But despite the rising death toll, the government's scientific advisory group for emergencies (SAGE) said on Friday that the virus reproduction (R) number had fallen from between 1.2 and 1.3 to between 0.8 and 1.0.

Although this suggests lockdown is working, experts have warned that restrictions are still a long way from being eased - as hospitals are still in crisis - and that more could be necessary to keep numbers down.

Rowland Kao, professor of veterinary epidemiology at the University of Edinburgh, said: "While the recent results showing declining case numbers is good news, and suggest that the variant is controllable via existing measures, these results on deaths imply that burden in hospitals will continue to be high requiring a more prolonged period of restrictions."

SAGE member and former chief scientific advisor Sir Mark Walport told the BBC: "If the evidence shows that the decrease in cases isn't continuing, then clearly policymakers will have to consider much tougher measures."