The Netherlands banned flights from the U.K. for at least the rest of the year while Belgium issued a flight ban for 24 hours starting at midnight and also halted train links to Britain, including the Eurostar. Austria and Italy said they would halt flights from the UK but did not give details on any timing of the ban.

Italian Foreign Minister Luigi Di Maio said on Twitter that the government was preparing the measure “to protect Italians” from the new coronavirus variant. About two dozen flights were scheduled to arrive in Italy on Sunday, most in the northern region of Lombardy but also in Veneto and Lazio, which include Venice and Rome respectively.

German officials, meanwhile, were considering “serious options” regarding incoming flights from the UK, but have not yet taken action.

The Czech Republic, meanwhile, imposed stricter quarantine measures from people arriving from the U.K.

The EU governments say they are acting in response to tougher measures imposed Saturday in London and its surrounding areas by British Prime Minister Boris Johnson. He immediately put those regions into a new Tier 4 level of restrictions, saying that a fast-moving new variant of the virus that is 70 per cent more transmissible than existing strains appears to be driving the rapid spread of new infections in London and southern England.

“There's no evidence to suggest it is more lethal or causes more severe illness,” Johnson said, or that vaccines will be less effective against it.

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

“There are a great many questions about this new mutation and if it is not already on the mainland,” he said. He hoped to have more clarity by Tuesday.

The World Health Organisation tweeted late Saturday that "We're in close contact with UK officials on the new #COVID19 virus variant." It promised to update governments and the public as more is learned about this variant.

The new strain of coronavirus was identified in southeastern England in September and has been circulating in the area since, a WHO official told the BBC on Sunday.

“What we understand is that it does have increased transmissibility, in terms of its ability to spread,” said Maria Van Kerkhove, WHO's technical lead on COVID-19.

Studies are under way to better understand how fast it spreads and and whether “it's related to the variant itself, or a combination of factors with behavior,” she said.

She said the strain had also been identified in Denmark, the Netherlands and Australia, where there was one case that did not spread further.