New corona-strain already in EU, as UK locked off

"There is an obvious risk that Danes will be tempted to cross over to Sweden to shop for Christmas presents or spend time in Malmö, for instance," he added.

Isolated cases of the mutated virus have also been detected in Belgium, Italy, the Netherlands, and Australia, national and World Health Organisation officials said the same day.

And other EU countries were expected to find ones soon.

"Why shouldn't it be [also] in Germany?", Christian Drosten, a virologist at the Charité Hospital in Berlin told the Deutsche Welle news agency.

"I think we will find, in the coming days, that a lot of other countries will find it," Belgian virologist Marc Van Ranst told Belgian broadcaster VRT.

The new strain was said to be 70 percent more contagious, British experts have said.

But virologists also said not to panic, as there were no signs it was either more lethal or vaccine-resistant.

Its detection, in the UK, on Sunday, still saw more than 40 countries, including most EU states, as well as ones as far afield as Argentina, Canada, India, Saudi Arabia, and Turkey abruptly cancel flights, trains, and ferries to Britain.

France also banned freight transport, creating tailbacks of lorries, and prompting alarm on shortages of fresh vegetables and citrus fruit in British retailers.

"I want to stress we in the UK fully understand our friends' anxieties about the new variant. But it's also true that the risks of transmission sitting alone in the [lorry] cab is very low," Johnson told press in Downing Street after speaking with French president Emmanuel Macron by phone.

"British supermarkets have said their supply chains are strong and robust, so everyone can continue to shop normally," Johnson added.

He was shown next to a headline saying "Sick Man of Europe" on the front page of the Daily Mirror, a British tabloid, however, highlighting the politics of the health crisis.

"French show no merci", British tabloid The Sun's headline added, linking the health crisis to Brexit, amid tense EU negotiations.

"It's a tragedy what's happening in Britain, and this Brexit is a tragedy, we see it more and more every day," France's EU commissioner, Thierry Breton, also said on Monday.

"Consider that if Great Britain had remained as we wished [in the EU], it would have today, like all other European countries, between €30bn and €50bn in aid thanks to the Next Generation EU fund set up by the [European] Commission," he added.

"We will have a [Brexit] agreement, but what a waste of time," Breton said.

EU states' officials were due to hold talks on the UK situation in the EU Council in Brussels on Tuesday.

Experts from the European Centre for Disease Prevention and Control, an EU agency in Stockholm, already briefed them in a three-hour meeting on Monday.

Despite the Swedish border closure, EU states agreed to try to keep free movement in the so-called Schengen travel zone, an EU diplomat told British newspaper The Guardian.

They also agreed on repatriating any EU citizens in the UK who wanted to come home.