People arriving in the UK from a number of coronavirus hotspots will be required to quarantine in government-run hotels at their own expense, Boris Johnson has announced.
It will apply to UK citizens and residents arriving from destinations including Portugal, South Africa and parts of South America.
Arrivals will have to quarantine for 10-days.
Labour has already attacked the decision to only target a limited number of countries as “half-baked” as it leaves “gaping holes” at the border.
People who want to travel out of the UK will also now have to make a declaration as to why they need to leave.
Priti Patel, the home secretary, said: “Going on holiday is not an exemption and it’s important that people stay at home.
“People should be staying at home unless they have a valid reason to leave.”
Speaking in the Commons on Wednesday, Johnson said: “I want to make clear that under the stay at home regulations, it is illegal to leave home to travel abroad for leisure purposes and we will enforce this at ports and airports by asking people why they are leaving and instructing them to return home if they do not have a valid reason to travel.
“We have also banned all travel from 22 countries where there is a risk of known variants including South Africa, Portugal and South American nations.
“And in order to reduce the risk posed by UK nationals and residents returning home from these countries, I can announce that we will require all such arrivals who cannot be refused entry to isolate in government provided accommodation, such as hotels, for 10 days without exception.
“They will be met at the airport and transported directly into quarantine.”
It comes after government figures showed more than 100,000 people in the UK have died within 28 days of testing positive for coronavirus since the pandemic began.
Australia became one of the first countries to introduce mandatory hotel quarantine in March 2020.
The practice is also observed in New Zealand, China, India, Singapore, the Philippines, Taiwan, Qatar and Thailand.
Direct flights to the UK from South Africa, Brazil and Portugal have already been suspended.
But British residents have been permitted to return through indirect routes and then self-isolate at home.