Britain is becoming increasingly isolated as more countries ban travel there amid tightened lockdown restrictions and fears for a virulent new strain of COVID-19.

On Monday (Australian time), Canada joined a growing list of European Union nations barring travel to and from Britain, with more considering similar action.

France, Germany, Italy, the Netherlands, Belgium, Austria, Ireland and Bulgaria all announced restrictions on British travel, hours after Prime Minister Boris Johnson announced that Christmas shopping and gatherings in southern England must be cancelled because of rapidly spreading infections blamed on the new coronavirus variant.

Mr Johnson immediately placed that region under a strict new Tier 4 restriction level, upending Christmas plans for millions.

France banned all travel from Britain for 48 hours from midnight Sunday. That included trucks carrying freight through the tunnel under the English Channel and travelling from the port of Dover on England’s south coast.

French officials said the pause would buy time to find a “common doctrine” on how to deal with the threat, but it threw the busy cross-channel route used by thousands of trucks a day into chaos.

Eurostar passenger trains from London to Paris, Brussels and Amsterdam were also halted.

Germany said all flights coming from Britain, except those carrying only cargo, were no longer allowed to land starting midnight Sunday. It didn’t immediately say how long the flight ban would last.

Belgian Prime Minister Alexander De Croo said he was issuing a flight ban for 24 hours starting at midnight “out of precaution”.

Canadian Prime Minister Justin Trudeau later said that for 72 hours starting at midnight Sunday, “all flights from the UK will be prohibited from entering Canada”.

He added that travellers who arrived on Sunday would be subject to secondary screening and other health measures.

The British government said Mr Johnson would preside at a meeting of the government’s crisis committee, COBRA, on Monday following the other nations’ measures.

Mr Johnson said on Saturday that a fast-moving new variant of the virus that is 70 per cent more transmissible than existing strains appeared to be driving the rapid spread of new infections in London and southern England in recent weeks.

But he stressed “there’s no evidence to suggest it is more lethal or causes more severe illness”, or that vaccines would be less effective against it.

Trucks queue to cross the English Channel at Dover on Friday. Photo: Getty

A World Health Organisation official confirmed to the BBC on Sunday the strain had been identified in Australia, where there was one case that didn’t spread further.

NSW chief health officer Kerry Chant confirmed on Monday that the state had “a couple of” returned British travellers who were infected with the new strain.

Britain recorded 35,928 further confirmed coronavirus cases, around double the number from a week ago.

In other developments:

• The Netherlands has also banned flights from Britain for at least the rest of 2020;
• Ireland issued a 48-hour flight ban;
• Italy said it would block flights from Britain until January 6, and an order prohibits entry into Italy by anyone who has been in Britain in the past 14 days.
• The Czech Republic has imposed stricter quarantine measures from people arriving from Britain.
• Israel also said it was banning flights from Britain, Denmark and South Africa because those were the countries where the mutation is found.

-with AAP