All travel corridors will close from Monday, meaning everyone arriving in the UK will have to self-isolate.
The tighter border restrictions announced by Boris Johnson are aimed at protecting the progress made with the rollout of vaccines in the face of new coronavirus variants being found around the world.
Everyone will also need to have proof of a negative COVID-19 test, as was previously announced.
Mr. Johnson told the Downing Street news briefing: "It's precisely because we have the hope of that vaccine and the risk of new strains coming from overseas that we must take additional steps now to stop those strains from entering the country.
"Yesterday we announced that we're banning flights from South America and Portugal and to protect us against the risk from as-yet-unidentified strains we will also temporarily close all travel corridors from 4am on Monday.
"Following conversations with the devolved administrations, we will act together so this applies across the whole of the UK."
The UK had previously closed its borders to travellers from South America, Cape Verde and Portugal - including Maderia, following news of a new COVID-19 variant in Brazil. That ban has now been extended to prevent any further variants from entering the UK.
The UK's Department for Transport has told us the Channel Islands are exempt from the restrictions, as part of the Common Travel Area.
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