Ireland on Tuesday said that from Saturday all arriving travellers will have to show a negative coronavirus test because the country's infection rate is now the highest in the world.
In the first such blanket restriction, the Irish government said all travellers would need to show a negative test result from within the past 72 hours.
This now applies to travellers only from the UK and South Africa, where new highly infectious strains were detected.
Travellers from those countries will still have to quarantine for 14 days on arrival, even after showing a negative test result.
Ireland, a country of five million, in December had the lowest infection rate in the EU but the number of cases has soared since restrictions were greatly eased over the festive period.
The number of confirmed cases rose from just over 93,000 on January 1 to more than 150,000 on Monday.
The number of cases for every million of population is 1,288, the highest in the world, University of Oxford data shows.
On Tuesday, Switzerland announced a quarantine on Irish travellers as World Health Organisation emergencies director Michael Ryan said the nation had "one of the most acute increases in disease incidence of any country".