Boris Johnson will host a Downing Street press conference on Friday afternoon, No.10 has announced. 

The prime minister has repeatedly warned England’s national lockdown rules could be tightened if they are not “properly observed”.

Priti Patel, the home secretary, said on Thursday tougher rules would not be introduced “today or tomorrow”. But she did not rule out new measures being announced next week.

Keir Starmer, the Labour leader, has said the current measures in England are “not strong enough” and accused the prime minister of being “slow to act”.

Scotland has toughened its lockdown restrictions to include reducing click and collect services to only those deemed essential from Saturday.

The latest data suggested infections have decreased in every region of England for the first time during the second wave of the virus.

It comes as Downing Street said that scientists at the government’s Porton Down research facility are investigating the new Brazilian variant of coronavirus.

“As with some of the other variants we’ve seen, the Kent variant and the South Africa variant, evidence does suggest that it may be more transmissible,” the prime minister’s official spokesperson said.

No.10 insisted it acted “as quickly as possible” to impose a ban on travellers from South America, which came into force on Friday.

But opposition parties have accused the government of acting far too slowly given the new variant was first revealed on Sunday.

The government has also been forced to defend the delay in requiring negative tests from travellers before they head to the UK from Friday until Monday as a “small grace period” needed to prevent a “repatriation crisis”.