London has reverted back to lockdown after news of a new COVID-19 strain came around, but the British government's chief scientific adviser believes more restrictions are likely.

Sir Patrick Vallance, the UK government's chief scientific adviser, said "it is likely" that instead of reducing restrictions in the next few weeks, "measures will need to be increased in some places."

Vallance said the possibility of further anti-coronavirus regulations being implemented would rely on the transmission across Britain.

London and some parts of England were placed on tier-4 lockdown over the weekend as the government scrambled to contain the new coronavirus strain that is said to be up to 70% more transmissible.

Despite worldwide concerns about the new strain British Prime Minister Boris Johnson attempted Monday to assure neighboring Europe nations his government had the situation in control.

Johnson said he had a "very good call" with French President Emmanuel Macron earlier in the day. France halted British entries to the country after the new strain emerged. The Netherlands, Germany, Bulgaria, Italy and Belgium banned entry from the UK on Sunday.

Canada said it was cancelling flights from Britain for 72 hours.

Meanwhile, calls have been made for a national lockdown in England as the new variant continues to spread across the UK.

The new coronavirus strain detected in September in Britain continues to cause concern. Within hours after the London lockdown thousands of people were photographed at railway stations and airports.

The increased number of flights being booked prompted neighboring governments to block travelers from the UK.