Passengers arriving in the UK from 33 high-risk countries will now have to quarantine in a hotel for 10 days.
The government says it is to help prevent the spread of highly contagious variants of COVID-19.
But the policy, which came into force on Monday, is attracting criticism for the way it has been organized.
A spokesman for London’s Heathrow Airport warned of “significant gaps” in the implementation plan.
Al Jazeera’s Paul Brennan reports from London’s Heathrow Airport, UK.
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