The World Health Organization says three types of coronavirus variant are spreading around the world, and an "escape mutation" that may make vaccines less effective against the virus has been identified.
The WHO report says a variant first found in Britain had been confirmed 83 countries and regions as of Tuesday. That is an increase of eight countries from last week.
Another variant first detected in South Africa was confirmed in 37 countries and regions, up three from last week.
Another variant found in Brazil and Japan was confirmed in 14 countries and regions, a rise of four nations from last week.
The report says a mutation previously found in the South Africa and Brazil variants was also detected in the British variant. The so-called escape mutation may decrease the efficacy of antibodies.
The WHO said it will study the impact of the variants on the effectiveness of vaccines and stressed the importance of stringent anti-infection measures.
In Japan, 13 people were confirmed to be infected with the variant on Tuesday. A total of 105 cases of variant infections have so far been found, including 43 at airport quarantine checks and 62 outside airports.
The head of the National Institute of Infectious Diseases, Wakita Takaji, told reporters on Tuesday that the variant has been detected in many parts of Japan, but infection routes are being traced in most cases. He said he believes that infection with the variant is not spreading in communities.