Millions more people in England will face escalated Covid-19 lockdown measures from St Stephen's Day, as ministers acknowledged mounting concern about the spread of coronavirus.

Health Secretary Matt Hancock said the variant coronavirus was spreading at a "dangerous rate" as he announced the fresh Tier 4 restrictions.

He also said cases of another new mutant coronavirus linked to South Africa had been found in Britain, and imposed new travel restrictions for the country.

Mr Hancock's announcement came as a further 40,000 cases were confirmed across the UK, as well as 744 deaths - the highest number since April.

Areas moving to the toughest Tier 4 measures, where there is a stay at home order, from St Stephen's Day include Sussex, Oxfordshire, Suffolk, Norfolk and Cambridgeshire.

Other areas include parts of Essex that are not yet in Tier 4, Waverley in Surrey and Hampshire, including Portsmouth and Southampton.

Bristol, Gloucestershire, Somerset including the North Somerset council area, Swindon, the Isle of Wight, the New Forest and Northamptonshire as well as Cheshire and Warrington will all be escalated to Tier 3.

Cornwall and Herefordshire move from Tier 1 to Tier 2.

Mr Hancock told a Downing Street press conference: "Just as we had got a tiered system in place that was able to control this virus we have discovered a new, more contagious virus - a variant that is spreading at a dangerous rate."

He said both are contacts of cases who have travelled from South Africa over the last few weeks.

"This new variant is highly concerning because it is yet more transmissible and it appears to have mutated further than the (first) new variant that's been discovered in the UK," Mr Hancock said.

He added: "Against this backdrop of rising infections, rising hospitalisations and rising numbers of people dying from coronavirus it is absolutely vital that we act.

"We simply cannot have the kind of Christmas that we all yearn for."

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Mr Hancock also said the Oxford/AstraZeneca vaccine has now submitted full data to the regulator for approval.

"Amid all this difficulty, the great hope for 2021 is of course the vaccine," he said.

He added: "The vaccine is our route out of all this and however tough this Christmas and this winter is going to be, we know that the transforming force of science is helping to find a way through.

"I'm delighted to be able to tell you that the Oxford/AstraZeneca vaccine developed here in the UK has submitted its full data package to the MHRA for approval.

"This is the next step towards a decision on the deployment of the vaccine which is already being manufactured, including here in the UK."

Meanwhile, the British government has implemented a travel ban on passengers arriving in England from South Africa after two cases of another new strain of Covid-19 linked to the country were identified in the UK.

It is believed to be behind an increase in cases in South Africa, and has been discovered in two people in the UK thought to be contacts of those who travelled between the two countries in the last few weeks.

From 9am on Christmas Eve, visitors arriving into England who have been in or transited through South Africa in the previous 10 days will not be permitted entry and direct flights will be banned, the Department for Transport (DfT) said.