A dedicated terminal for passengers arriving in the UK from countries with a high risk of Covid has opened at Heathrow Airport.
Travellers arriving on direct flights from red list nations will now transit through Terminal Three.
Heathrow said its top priority was protecting the public and helping reduce the risk of new variants.
There are 43 countries on the red list, but direct flights are permitted from only India, Pakistan and Bangladesh.
Direct flights are also allowed from Kenya, but the country has currently suspended air travel to the UK.
Only British and Irish nationals or UK residents are allowed to travel from countries on the list.
But anyone who has been in a red list country in the previous 10 days, whether they took a direct flight or came via another country, is required to pay for quarantine in a hotel for 10 nights after their arrival.
However, there has been concern at reports that travellers from red list areas were mixing with other passengers in immigration halls, where they could be waiting for several hours on occasion.
It comes as a scientist advising the UK government warned of signs the country is in the early stages of a third wave of coronavirus infections.
A Heathrow Airport spokeswoman said: “Red list routes will likely be a feature of UK travel for the foreseeable future as countries vaccinate their populations at different rates.
“We’re adapting Heathrow to this longer-term reality by initially opening a dedicated arrivals facility.”
She added that while opening the facility would be “logistically very challenging”, Heathrow hoped that doing so would enable Border Force to carry out its duties more efficiently, as passenger volumes increase in line with countries on the government’s green list.
But for now, the current red list system would continue, including mandatory negative Covid tests for all international arrivals, mandatory use of face coverings, social distancing, segregation and enhanced cleaning regimes and ventilation in immigration halls.
Heathrow added that its dedicated arrivals site would switched to Terminal 4 “as soon as operationally possible”.