Direct flights to the UK from South Africa, Brazil and Portugal have already been suspended, but British residents have been permitted to return through indirect routes and then self-isolate at home.
More widely, anyone entering the country from abroad, including UK nationals returning home, must provide proof of a negative Covid-19 test result taken up to three days before departure.
Travellers must also self-isolate for 10 days upon arrival even if they tested negative.
An exemption from self-isolation applies for people heading to England from Ireland, the Channel Islands or the Isle of Man.
In England, travellers may be able to end self-isolation early if they pay for a private coronavirus test.