Prime Minister Boris Johnson today said there was "some evidence" that the UK variant of coronavirus is associated with a "higher degree of mortality".

Speaking at a Downing Street press conference, he said the impact of the variant was "largely the reason" why the NHS was under unprecedented pressure.

He said: "I must tell you this afternoon that we’ve been informed today that in addition to spreading more quickly it also now appears that there is some evidence that the new variant, the variant that was first identified in London and the South East, may be associated with a higher degree of mortality.”

Government Chief Scientific Adviser Patrick Vallance reminded the briefing there are three variants of potential concern - one identified in the UK, one in Brazil and South Africa.

He said the UK variant was now a "common one, comprising a significant number of cases".

He said: "It doesn't have a difference in terms of age distribution, similarly to the original virus.

"There is evidence that there is an increased risk for those who have the new variant compared to the original virus. That evidence is not yet strong."

In the case of a man in his 60s, he said the average risk is that for 1,000 people who got infected, ten would be expected to die with the virus.

For the new variant roughly 13 or 14 might be expected to die.

He added: "I want to stress that there's a lot of uncertainty around these numbers but it obviously is a concern."

Boris Johnson said there are 38,562 Covid patients in hospital, 78% higher than in the first peak in April.

The Prime Minister said: “It’s more important than ever that we all remain vigilant in following the rules and that we stay at home, protect the NHS and thereby save lives.”

He added: “All current evidence continues to show that both the vaccines we’re currently using remain effective both against the old variant and this new variant.”