A number of European countries have or are considering banning travel from the UK to prevent the spread of a more infectious variant of coronavirus.
Both the Netherlands and Belgium have suspended flights. Trains to Belgium have also been banned.
Italy's foreign minister has indicated his government plans to ban flights. France and Germany are reportedly planning similar action, reports BBC.
The new variant has spread fast in London and south-East England.
British Prime Minister Boris Johnson on Saturday introduced a new tier four level of restrictions, scrapping a planned relaxation of rules over the Christmas period for millions of people.
Top health officials said that there was no evidence the new variant was more deadly, or would react differently to vaccines, but it was proving to be up to 70% more transmissible.
The WHO says the same mutation has also been detected in the Netherlands, Denmark and Australia.
Within hours of the UK announcement, the Netherlands said it would ban all passenger flights from the UK from 06:00 (05:00 GMT) on Sunday until January 1.
Pending "greater clarity" on the situation in the UK, the Dutch government said that further "risk of the new virus strain being introduced to the Netherlands should be minimised as much as possible".
It also said it would work with other European Union member states in the coming days to "explore the scope for further limiting the risk of the new strain of the virus being brought over from the UK".
Belgium is suspending flights and train arrivals from the UK from midnight (23:00 GMT) Sunday. Prime Minister Alexander De Croo told Belgian television channel VRT the ban would be in place for at least 24 hours and "is a precautionary measure", adding "we will see later if we need additional measures".
Meanwhile, Italy's Foreign Minister Luigi Di Maio said on his Facebook page that the government was about to sign a measure to suspend flights from the UK.
In Germany, a health ministry official said that the government was also considering banning flights from the UK, and South Africa, where the variant has also been detected.
The official said the German government was monitoring developments in the UK and working at "high pressure" to evaluate the new information and data regarding the new variant.
The French news channel BFMTV reported that France too was "seriously" considering suspending flights and trains from the UK, and the government was "looking for European coordination".
"A decision will be announced during the day," the channel said.
