Thailand and Montenegro are being added to the government’s red travel list, while the Azores, Switzerland, Denmark and Canada are among seven locations being moved to the green list, the Department for Transport said.
It means people returning to the UK from “red” destinations will be forced to enter a quarantine hotel.
Popular European holiday destinations including Spain, France and Greece have remained on the amber list.
All arrivals from green list locations must take a pre-departure test and another after they land.
Those travelling from an amber country must take the same tests, plus a second post-arrival test.
This article originally appeared on HuffPost UK and has been updated.