Ireland - Flights from Britain from midnight were banned for at least 48 hours. The country shares a highly-porous 499-kilometre (310-mile) border with the UK.
Italy - Italian Health Minister Roberto Speranza said that he had signed a decree "which blocks flights from Great Britain and prohibits entry into Italy of people who has stayed there during the last 14 days".
Anyone in Italy who recently traveled from Britain must be tested, the statement added.
The new strain has been found in one person in Italy who recently returned from the UK.
Rest of Europe - Elsewhere in Europe, Belgium banned flights from the UK for 24 hours, Finland barred flights for two weeks and Switzerland stopped them until further notice.
Estonia, Latvia, and Lithuania have halted flights, with Croatia suspending them for 48 hours.
Bulgaria said flights to and from Britain would be suspended until January 31.
Romania is banning all flights to and from the UK for two weeks from Monday afternoon.
Canada - Prime Minister Justin Trudeau said that Canada would ban all UK flights for 72 hours.
In a tweet, he added those who had already arrived from Britain on Sunday would be subject to secondary screenings and other "advanced measures".
Turkey - Turkey's Health Minister Fahrettin Koca said that flights from Britain, Denmark -- where nine cases of the new strain have been detected -- the Netherlands, and South Africa would be suspended.
Iran - Iran's health ministry has ordered flights from Britain suspended for two weeks.
Saudi Arabia - Saudi Arabia said it was halting all flights and entry through land and sea ports for at least a week, with the option to extend for a further week.
Passengers who arrived in the kingdom from Europe -- or any country where the new strain was detected -- will be required to self isolate for two weeks and undergo testing.
Kuwait - Kuwait has added Britain to a list of "high-risk" nations and banned flights.
El Salvador - El Salvador's President Nayib Bukele said that anyone who had been in Britain or South Africa in the past 30 days will not be allowed to enter the country.
Argentina - Argentina has banned flights from the UK.
It said the last flight from Britain would arrive in the country on Monday.
Chile - Chile is suspending flights from the UK from Tuesday.
The government said anyone without a Chilean residence permit who had been in Britain in the past two weeks would be barred from entry into the country.
Morocco - Morocco banned all flights to the UK from Sunday.