Denmark, Slovakia and Iceland have been removed from the UK’s travel corridor list, Transport secretary Grant Shapps has announced.
The Caribbean island of Curacao has also been removed.
Any travellers arriving in the UK from these countries as of 4am on Saturday will need to self-isolate for 14 days.
The new rules come amid a surge in Covid-19 cases in these countries, with the Department for Transport warning there had been a 921% increase in infections per 100,000 people in Iceland over the past week.
Meanwhile, the government warned there had been a 115% increase in cases in recent weeks in Slovakia and a 508% jump in Denmark over the past month.
In Curaçao, a small Caribbean island off the coast of Venezuela, there had been a 481% increase in newly reported coronavirus cases between September 2 and 23.
The Foreign, Commonwealth and Development Office now advises against all but essential travel to all four countries.