More than a quarter of the UK population will be living under extra coronavirus restrictions when new measures on socialising come into force.

It comes as the UK recorded its highest single-day figure of coronavirus cases, with 6,874 lab-confirmed cases.

Restrictions are already in force across Scotland and in large swathes of north-west England, West Yorkshire, the North East and the Midlands.

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Residents in those areas are also advised not to meet people outside their household or bubble in any other settings including bars, shops or parks.

And a ban on households mixing indoors was extended across Northern Ireland earlier this week.

Cardiff and Swansea will go into local lockdown from 6pm on Sunday, the Welsh Government has confirmed.

People will not be able to enter or leave the areas without a reasonable excuse. They will not be able to meet indoors with anyone they do not live with, with extended households suspended.

The total number of people set to be living under stricter rules will rise to 17 million.

Health Secretary Matt Hancock said there had been an “acceleration of Covid-19 cases across the country, especially in the North West and the North East”.

“Working alongside our scientific and public health experts and local leaders, we are prepared to take swift and decisive action to reduce transmission of the virus and protect communities.

“I recognise the burden and impact these additional measures have on our daily lives but we must act collectively and quickly to bring down infections.”

It comes as all London boroughs were added to the Government’s list of areas of concern following a rise in cases in the city.

The new status means the capital could receive extra testing and other help such as engagement with high-risk groups as a result of rising Covid-19 cases.

Meanwhile, infectious disease modelling expert Professor Graham Medley warned there would be 100 coronavirus deaths a day in a few weeks’ time.

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Prof Medley, who attends meetings of the Scientific Advisory Group for Emergencies (Sage), told BBC Radio 4’s Today programme that the new restrictions would not stop the deaths but would prevent the toll getting even higher.

“A level of 10,000 (cases) we are seeing now means that in three or four weeks we are going to see 100 deaths a day.

“In order to stop that process increasing again, then we need to make sure that that transmission comes down now because that doubling time will carry on. The things that we do now will not stop 100 people dying a day but they will stop that progressing much higher.”

He also said he had “never heard” the 10pm curfew for hospitality discussed during Sage meetings.