Japanese citizens and foreign residents can still enter, but are expected to be quarantined for 14 days, according to Japanese public broadcaster NHK.
The shift came after the Tokyo metropolitan government on Saturday confirmed two new cases of the Covid-19 variant involving people who recently returned from the UK.
The two new cases were the first to be discovered outside the country’s airport quarantine.
On Friday, five other British travelers were detected with the variant at Japanese international airports.
Restrictions of varying degrees have been announced by countries such as Denmark, Ecuador, Greece, Portugal, Spain and Ukraine. Still 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 travel restrictions on South Africa, where a different variant has been reported, according to Maria van Kerkhove of the World Health Organization.