The United Kingdom was stuck in Covid-19 isolation on Tuesday after much of the world cut off travel ties due to a highly infectious new coronavirus strain, halting one of Europe's most important trade routes just days before the Brexit cliff edge.

With queues of trucks snaking to the horizon in England and supermarket shelves stripped just days before Christmas, British Prime Minister Boris Johnson scrambled to get French President Emmanuel Macron to lift a ban on freight from Britain.

Johnson and his advisers said the mutated variant of the novel coronavirus, which could be up to 70% more transmissible, was spreading rapidly but that it had been identified because British scientists were so efficient at genomic surveillance.

The BBC cited France's Europe Minister Clément Beaune as saying that Britain and France would announce a deal to restart freight by Wednesday.

"We speak to our colleagues in France constantly on a range of issues and that work has been underway over the last 24 hours and we'll continue today," British Home Secretary Priti Patel told Sky News. "We'll see what materialises today."

Asked if there would be an agreement on Tuesday, Patel said: "We're working to get a resolution. It's in both our interests to ensure that we have flow."

One option is to roll out mass Covid-19 testing for truck drivers, though such tests usually take 24-48 hours for a result so it was not immediately clear how swiftly trucks could be moving again with Christmas days away.

Johnson spoke to Macron on Monday about lifting the freight ban, adding that the French leader wanted to move within hours. Patel said details could be announced later on Tuesday.

The discovery of the new strain, just months before vaccines are expected to be widely available, sowed a fresh wave of panic in a pandemic that has killed about 1.7 million people worldwide and more than 67,000 in Britain.

The main worry is that the variant is significantly more transmissible than the original strain.

Scientists say there's no evidence that vaccines currently being deployed in the UK - made by Pfizer and BioNTech - or other Covid-19 shots in development will not protect against this variant, known as the B.1.1.7 lineage.

FOOD SUPPLY WORRIES

The United Kingdom is in effective Covid-19 quarantine just nine days before it is due to part ways with the EU after a transition period - considered to be one of the biggest changes in post-World War Two British history.

Countries across Europe and beyond have suspended travel from Britain since the weekend. Germany imposed a ban on UK travellers from Tuesday that could remain in place until Jan. 6.

Cases of the new strain have also been detected in some other countries, including Denmark and Italy. Experts said the prevalence found in Britain might be down to better detection.

Britain's border crisis led to some panic-buying in the country: shoppers stripped shelves in some supermarkets of turkey, toilet roll, bread and vegetables.

While the government said there was enough food for Christmas, market leader Tesco and No. 2 player Sainsbury's both said food supplies would be affected if the disruption continued.

Supermarkets are seeking to source more from Britain and looking into alternative transport for produce from Europe, including using ferries directly from Spain and increasing stock from the Netherlands.

'GET THESE GUYS HOME'

Patel said 650 trucks were stacked up on the M20 in Kent, southern England, and 873 at the nearby Manston Airport.

"Lorry drivers are a really good, resilient, self sufficient bunch," Doug Bannister, CEO of the Port of Dover, told Times Radio, adding that something should be done to get these "really heroic guys home for their Christmas break".

While trucks can still cross from France into Britain, they cannot return so European truck drivers are extremely reluctant to travel.

As the sun rose, hundreds of stranded drivers waiting to be allowed to cross to France via either ferry or the Channel Tunnel brewed tea and coffee after a night spent on the M20 motorway.

Drivers said they just wanted to get back home in time for Christmas.

"My chances of going home for Christmas are going down. It's stupid and I am nervous and unhappy about that," Stanislaw Olbrich, a 55-year-old Polish trucker stuck 24 miles (40 km) north of Dover, told Reuters.