LONDON — London's Heathrow Airport has reopened a terminal that was mothballed during the coronavirus pandemic to handle passengers now arriving from high-risk countries. Critics say the action should have been taken sooner.

Britain has barred travelers from a “red list” of 43 coronavirus hotspots including India, Brazil and Turkey. U.K. nationals and residents returning from those countries face a mandatory 10-day quarantine in a hotel. Other travelers coming from “amber list” countries like the United States can do their mandatory 10-day quarantine at home in the U.K.

Critics have complained that red list passengers have been using the same massive airport arrivals hall as travelers from other destinations, though in separate lines, since the hotel quarantines were introduced in February.

Starting Tuesday, red list arrivals will pass through the airport’s Terminal 3, which was closed in April 2020 as international air travel plummeted.