Travellers coming from Croatia and Austria to the UK will now have to self-isolate for two weeks – while those coming from Portugal no longer face restrictions.
Anyone returning to the UK from Trinidad and Tobago will also have to quarantine for 14 days.
The restrictions come into force at 4am on Saturday.
Croatia’s average number of cases has risen to 29.5 cases per 100,000 people in the past week – compared to a rate of 13.54 per 100,000 a week ago.
The Foreign Office has said it would look at putting any country with more than 20 cases per 100,000 people on its quarantine list.