The Irish government has enforced quarantine restrictions for Greece and six other countries.
As of Monday 21 September travellers from Estonia, Greenland, Hungary, Italy, Norway, Slovakia and Greece will have to isolate for 14 days after arriving in Ireland.
At the same time Cyprus, Finland, Germany, Iceland, Latvia, Lithuania and Poland are on Ireland's 'green list', where travellers arriving from these countries avoid quarantine.
This decision has been criticised by Ireland’s dominant airlines Ryanair and Aer Lingus.
In a statement Ryanairsaid: "Instead of adopting the EU traffic light system they promised to do only last Tuesday, they have today departed from that policy by taking Italy and Greece from the green list when both countries have Covid rates 60%+ less than Ireland and are also classified under the new EU system as having no travel restrictions within the EU."
"Today's announcement shows that the left hand of the Government doesn't know what its right hand is doing. There is no scientific basis behind the decision by Minister for Foreign Affairs Simon Coveney to remove Italy and Greece from the Green List only to add them back again in three weeks' time," it continued.
Ireland's Department of Foreign Affairs said the general advice remains that people should avoid non-essential travel, other than to countries on the Green List where the advice is to take normal precautions.