LONDON, Dec. 22 (Xinhua) -- Another 36,804 people in Britain have tested positive for COVID-19, marking the highest daily increase of coronavirus cases since the pandemic began in the country, according to official figures released Tuesday.

The total number of coronavirus cases in the country now stands at 2,110,314, the data showed.

Another 691 people have died within 28 days of a positive test, bringing the total number of coronavirus-related deaths in Britain to 68,307, the data showed.

The figures were revealed amid grave concerns over the fast spread of a new coronavirus strain in Britain, which is said to be about 70 percent more transmissible.

Thousands of cases of the more infectious variant of coronavirus have been detected across Britain, indicating that the new strain had clearly spread beyond areas under the toughest Tier Four restrictions, The Guardian newspaper reported.

"It is certainly not the case that this is just completely geographically constrained in what is the current Tier Four area," said Dr Jeffrey Barrett, a statistical geneticist working on COVID-19 at the Wellcome Trust's Sanger Institute near Cambridge.

More than 40 countries have imposed travel restrictions on travelers from Britain amid fears of the new virus strain.

France has closed its border with Britain for 48 hours, with no lorries or ferry passengers able to sail from the port of Dover. A deal to resume travel with France following the shutdown could come later Tuesday, according to Sky News.

British Prime Minister Boris Johnson on Saturday announced the new Tier Four restrictions for London and other parts of England to combat an alarming surge in infections linked to the new virulent strain. British Health Secretary Matt Hancock has warned that the new virus strain is "out of control" in Britain.

To bring life back to normal, countries such as Britain, China, Germany, Russia and the United States are racing against time to develop coronavirus vaccines.