According to Japanese public broadcaster NHK, Japanese citizens and foreign residents can still enter, but must be quarantined for 14 days.
The move came after the Tokyo metropolitan government on Saturday confirmed two new Covid-19 variant cases involving people who had recently returned from the UK.
The two new cases were the first to be discovered outside the country’s airport quarantine.
Five other passengers from Britain were detected on Friday with the variant at Japan’s international airports.
Countries such as Denmark, Ecuador, Greece, Portugal, Spain and Ukraine have announced restrictions of varying degrees. Others have banned travel or suspended flights from the UK, such as Argentina, Belgium, Brazil, Canada, China, Colombia, Germany, India, Italy, the Netherlands, Russia and Spain.
Others have extended travel bans or restrictions to other countries where the variant has been detected, such as Denmark, the Netherlands and Australia. Several countries have also imposed restrictions on travel from South Africa, where a different variant has been reported, according to Maria van Kerkhove of the World Health Organization.