Arrivals to England from 33 countries, including Portugal, now have to self-isolate for 10 days in a hotel they have pre-booked, at a cost of around €2,000.
A UK hotel quarantine for arrivals from countries deemed to be high risk due to coronavirus mutations has come into effect.
From Monday, arrivals in England from 33 countries will have to pay some €2,000 to self-isolate for 10 days in a pre-booked hotel room.
The list of countries includes Portugal, and arrivals from these countries have already been banned - with the exception of British residents or Irish citizens.
Breaking the rules could see people charged fines of up to €11,500 - or even face 10 years in prison, according to the UK government.
As with all other travellers, in addition to having a negative test performed 72 hours prior to arrival, these arrivals must also be tested on the second and eighth days of the quarantine.
Travellers have to pre-book on a government website, which has already been reported to have crashed a number of times.
Questions have been raised as to why arrivals from red list countries are not separated from other passengers once they disembark the plane at UK airports.
Scotland has implemented a similar scheme, but extended it to arrivals from all countries.
More than 15 million vaccinated
The hotel quarantine has been designed to curb COVID-19 variants. Experts fear these could be more resistant to the vaccines currently being given in the UK.
The UK variant, which quickly became the dominant variant in the country and has now spread across the world, is just one of a number that are causing alarm to health experts.
The UK is racing ahead of many of its neighbours in its vaccination programme, with some 15 million people now vaccinated.
After having met the ambitious objective of offering a vaccine to the first four categories of the most vulnerable people before mid-February, the vaccination programme will be extended from Monday to people between the ages of 65 and 69.