Denmark has been removed from the Government's list of travel corridors following a surge in coronavirus cases, amid the spread of a "variant strain".
Travellers arriving in the UK from the Scandinavian country from 4am today must self-isolate for 14 days in a move done "quickly to protect our country", according to Transport Secretary Grant Shapps.
On Thursday, Britain also removed Germany and Sweden from its list of countries where travellers would not have to quarantine on arrival in England from 4am on Saturday.
Mr Shapps said: "I understand that this will be concerning for both people currently in Denmark and the wider UK public, which is why we have moved quickly to protect our country and prevent the spread of the virus to the UK.