Boris Johnson will host a press conference with his chief medical and scientific advisers on Saturday afternoon, amid speculation he will impose a national lockdown in England next week.

The Prime Minister is expected to be joined by Professor Chris Whitty and Sir Patrick Vallance in Downing Street at 4pm, following a meeting of his Cabinet earlier in the afternoon.

Mr Johnson has so far resisted pressure to introduce nationwide restrictions, opting instead for a localised tier system, but he is reportedly considering closing everything except essential shops and education settings for a month from Wednesday.

The policy shift comes after new data showed the extent of cases across England. The Office for National Statistics estimated that 568,100 people in households were infected with coronavirus in the week ending October 23.

Members of the Government's Scientific Advisory Group for Emergencies (Sage) have backed the introduction of more stringent measures.

Professor Sir Jeremy Farrar said the consequences of sticking with the current "insufficient" restrictions would be "much worse" than going for a second lockdown.

The director of the Wellcome Trust said: "The sooner we act, the sooner we can start to recover. It will be a very difficult few weeks now and no one can underestimate the toll that will take on people.

"But the consequences of sticking with the current insufficient restrictions would have been much worse."

Sage member Professor Calum Semple told BBC Radio 4's Today programme: "For the naysayers that don't believe in a second wave, there is a second wave.

"And, unlike the first wave, where we had a national lockdown which protected huge swathes of society, this outbreak is now running riot across all age groups."

Professor John Edmunds said the only way to have a "relatively safe" Christmas is to take "stringent" action now to bring the incidence of the virus "right down".