Travellers from South America, Portugal and Cape Verde have been barred from entering UK, amid fears over a new virus variant.
Scientists say its mutations seem to be associated with a rapid increase in cases, reports the BBC.
One of two variants discovered in Brazil has been detected in the UK, a leading virologist said.
Earlier UK minister Grant Shapps said he did not think the Brazilian variant was in the UK "as far as we are aware".
The health system in the Brazilian city of Manaus is said to be collapsing amid soaring infections linked to the new variant.