A further 612 Covid-19 deaths have been reported in the UK, along with 25,161 confirmed cases.

This is a jump from the 533 deaths and 16,578 cases announced last Wednesday, government data shows.

This is a jump from the 533 deaths and 16,578 cases announced last Wednesday, government data shows.

The cases and deaths by nation are as follows:

• Scotland - 689 cases, 38 deaths
• Northern Ireland - 510 cases, eight deaths
• England - 23,432 cases, 537 deaths
• Wales - 530 cases, 29 deaths

As the figures continue to rise, there have been fears that Christmas celebrations could set off another jump in cases.

After facing political pressure from doctors and Labour, Boris Johnson has resisted changing the relaxation of rules over the festive period - but warned "a smaller Christmas is going to be a safer Christmas".

Addressing the nation from Downing Street - flanked by England's chief medical officer Professor Chris Whitty - the prime minister called for people to reduce their contacts before celebrations, avoid overnight stays and stay local.

These points are guidance and will not be made law.

But in a blow to the four-nation approach to Christmas, Wales broke ranks and confirmed it will be putting its new guidance on limiting Christmas gatherings to two households into legislation.

Scotland has also recommended people forming a Christmas bubble should only meet on one day and avoid staying overnight, although this has not been put into law.

Dr Peter Drobac, global health expert at Oxford University, told Sky News it is "extremely likely we would see a rise in cases" over Christmas.

"What's important for everyone to understand is if we have a lot of travel and household mixing over the holiday period - because we just saw it after Thanksgiving in America - there could be rises in cases of 20 to 40% in the weeks afterwards.

"So we will pay a price in January if we're not very careful."

In another major announcement on Wednesday, the government has also confirmed that the tier restrictions will be reviewed for each area on Thursday.

London and parts of Hertfordshire and Essex have already been moved into Tier 3, the highest level of restrictions, after sharp increases in cases over recent days.