Thailand and Singapore have been added to the list of travel corridors after a decrease in the rate of coronavirus cases, Transport Secretary Grant Shapps has announced.
Travellers arriving in England from either south-east Asian country after 4am on Saturday will no longer need to self-isolate for 14 days.
But quarantine restrictions are being imposed on travellers from Slovenia and Guadeloupe.
The Department for Transport (DfT) said there has been "a significant change in both the level and pace of confirmed cases of coronavirus in both destinations".
Data from Slovenia shows that its seven-day rate of cases is 29.1 per 100,000 people, up from 14.4 in the previous seven days.
The rate for Guadeloupe has risen more than six-fold in the past four weeks, the DfT said.
A rate of 20 is the threshold above which the UK Government considers triggering quarantine conditions.
The decision to remove the quarantine requirement for arrivals from Thailand and Singapore is unlikely to lead in a surge of people from England visiting the destinations.
The countries are only allowing people to enter for a limited number of reasons, such as if they have a work permit or are the spouse or child of a resident.
If you arrive in England from...🇸🇮Slovenia🇬🇵Guadeloupeafter 04:00 19 Sept 2020, you must self-isolate for 14 days.
If you arrive from 🇸🇬Singapore or 🇹🇭Thailand after 04:00 19 Sept you will not need to self-isolate
— Dept for Transport (@transportgovuk) September 17, 2020
Denmark retained its quarantine exemption, despite its seven-day case rate being 33.8.
The DfT urged employers to be "understanding" of people returning from Slovenia and Guadeloupe, as they will need to self-isolate.
The statement gave no update on the possible introduction of testing at airports as a way of reducing quarantine requirements.
The travel industry has demanded this should take place urgently to avoid further job losses.
Earlier this week British Airways boss Alex Cruz called for trials to be held for passengers flying between London and New York.
He said "this is imperative", adding that the airline is "still fighting for our own survival".