Britain began its third lockdown on Tuesday after Prime Minister Boris Johnson said a coronavirus variant first identified in Britain was spreading so fast it risked overwhelming the National Health Service within 21 days.
UK scientists also expressed concern that vaccines being rolled out in Britain may not be able to protect against another variant that emerged in South Africa.
The following countries, in alphabetical order, are among those that have reported variants among their populations.
* AUSTRALIA said two travellers from the United Kingdom were carrying the variant found in Britain.
* AUSTRIA has found four cases of the coronavirus mutation first detected in Britain and one case of the South African mutation, Franz Allerberger of public health agency AGES told a news conference on Monday.
* BRAZIL confirmed its first two cases of British variant, Sao Paulo state's health secretariat said.
* Officials in CANADA said that two confirmed cases of the variant detected in the United Kingdom had appeared in the Canadian province of Ontario.
* CHILE said it had recorded its first case of the British variant.
* CYPRUS has discovered 12 cases of the variant in people who recently travelled from Britain.
* DENMARK estimates around 800 peoples have been infected with the variant spreading in Britain.
* Health officials in FINLAND said the variant circulating in Britain has been detected in two people, while the variant spreading in South Africa has been detected in one person.
* FRANCE said there were around a dozen cases of the UK variant in the country. Martin Hirsch, director general of the Paris hospitals system, said the variant was present in Paris.
* GERMANY said the variant from Britain had been found in a passenger flying to Frankfurt from London on Dec. 20. It seems to have been present in Germany since November, the Die Welt daily reported.
* GREECE has detected four cases of the variant in people who recently travelled from Britain, a Health Ministry official said.
* The British variant appears to have infected two students who returned to HONG KONG from the UK, the Department of Health said.
* INDIA has found 38 cases of the variant found in Britain.
* IRAN on Tuesday registered its first case of a coronavirus variant in a traveller arriving from the United Kingdom.
* Health officials in IRELAND said increased socialising around Christmas - and not a new variant - had driven a surge in infections. Prime Minister Micheál Martin said on Wednesday the variant discovered in Britain was spreading in Ireland at a rate that has surpassed the most pessimistic models available to the government.
* ISRAEL detected four cases of the coronavirus emerging in Britain.
* ITALY detected a patient infected with the variant found in Britain, the health ministry said.
* JAPAN detected the variant found in South Africa, the government said, the first such discovery in a nation that has already identified more than a dozen cases of the variant spreading in Britain.
* JORDAN has detected its first two cases of the variant spreading in Britain.
* LEBANON detected its first case of a variant of the coronavirus on a flight arriving from London.
* NORWAY said the variant circulating in Britain had been detected in 23 people, while the variant circulating in South Africa had been detected in one person.
* OMAN registered its first case of the variant that emerged in Britain, in a resident who arrived from the UK, the health ministry said on Tuesday
* PAKISTAN health officials said the variant found in Britain had been detected in the southern province of Sindh.
* The variant linked to Britain has been detected on the island of Madeira in PORTUGAL, the regional civil protection authority said.
* SINGAPORE confirmed its first case of the variant found in Britain, the patient arriving from Britain on Dec. 6, while 11 others who were already in quarantine had returned preliminarily positive results.
* SOUTH KOREA said the variant found in Britain was found in three people who had entered South Korea from London on Dec. 22. Officials vowed to speed up vaccinations.
* SWEDEN said the variant circulating in Britain had been detected after a traveller from Britain fell ill on arrival and tested positive.
* SWITZERLAND has recorded 28 cases of the variant circulating in Britain, Swiss health officials said on Tuesday. It has also recorded two cases of the South African mutation.
* Self-ruled TAIWAN, claimed by neighbouring China, confirmed its first case of the variant discovered in Britain, a traveller from the UK.
* TURKEY has banned Britons from entering the country after detecting 15 cases of the new variant in travellers from Britain, the government said.
* UNITED ARAB EMIRATES discovered a "limited number" of cases of people infected with a new variant, a government official said. Those affected had travelled from abroad, without specifying from where or the number of cases.
* The UNITED STATES has reported four cases of the UK variant - in New York, California, Florida and Colorado.
* VIETNAM has detected its first case of the variant that is spreading around Britain, the health ministry said.