Luxembourg’s travel corridor with the UK has been revoked, temporarily ending quarantine-free travel between the two countries.
Anyone arriving into the UK from Luxembourg will need to self-isolate for two weeks with immediate effect.
The Department for Transport said data from the UK’s Joint Biosecurity Centre and Public Health England has indicated "a significant change in both the level and pace of confirmed cases of coronavirus in Luxembourg".
"There has been a consistent increase in coronavirus (Covid-19) cases per 100,000 of the population in Luxembourg since the end of June, with over a tenfold increase in total cases over this time period," said the DfT.
"As a result, ministers took the decision to remove Luxembourg from the travel corridor list of countries from which people arriving in the UK do not have to self-isolate."
The move will be mirrored by the UK’s devolved administrations in Wales, Scotland and Northern Ireland.
The Foreign Office has also updated its travel advice to advise against all but essential travel to Luxembourg.
Anyone currently in the country should follow local rules and health measures, and check the FCO’s travel advice for further information.
The decision to reintroduce a return quarantine requirement for arrivals from Luxembourg comes after Serbia and Spain’s travel corridors were revoked earlier this month owing to increasing rates of coronavirus infection.
"The government has made consistently clear it will take decisive action if necessary to contain the virus, including removing countries rapidly if the public health risk of people returning from a particular country and not self-isolating becomes too high," said the DfT and the FCO in a joint statement.
Employers have been urged to show "understanding" for those returning from Luxembourg who will have to self-isolate.