Irish tourists returning from Cyprus and Malta today will need to restrict their movements for two weeks after confusion over changes made to the Green List.
Some travel agents and politicians believed the new list would only apply from Monday, allowing those who flew back before then to avoid having to quarantine for 14 days.
The Department of Foreign Affairs has now confirmed that the new list, which dropped five countries due to a spike in Covid-19 cases, came into effect immediately when announced this week.
It means travellers will now have to follow strict social distancing rules for two weeks.
On Tuesday, Malta, Cyprus, Gibraltar, San Marino and Monaco were removed from the list of countries that people can travel to without restricting their movements for two weeks afterwards.
There are direct flights from Ireland to Malta and Cyprus, which were popular tourist destinations this summer due to their low rate of Covid-19 infection.
However, both destinations are now experiencing a sudden spike in cases.
Travel agents, including Sunway, had advised clients they would not need to restrict their movements if they arrived home before Monday, August 10.
It said this week it had begun trying to arrange early flights home for holidaymakers.
The Herald has seen emails from a senator who told a constituent in Cyprus that the new Green List only came into effect from Monday.
A number of tourists said they had not yet been given clear advice, despite calling officials.
Wednesday saw some tour operators scramble to find alternative flights home for tourists in Cyprus and Malta after both countries were removed from the list
A number of Irish tourists were due to arrive home on flights today.
The news comes as Ryanair said it had restored 60pc of its scheduled flights for August.
The airline, which had been criticised for advertising sun holidays despite advice to avoid all non-essential travel, said it is operating 11,000 weekly flights on 1,600 routes.
It said it was enforcing the use of face masks on board, while also trying to reduce the number of passengers who were using cash to pay for in-flight services.
"We were pleased to see our people and customers adapt to our healthy flying measures, and we encourage all those travelling with us in August to continue to do so," said Ryanair's Eddie Wilson.