The European Commission has urged Ireland to pursue less restrictive measures than the mandatory hotel quarantine regime introduced last month.
On Friday, it sought clarifications as to why some fellow EU member states were subject to the rules.
Ireland is the only one the EU's 27 countries that requires arrivals from certain countries to pay almost €2,000 each to quarantine for up to 14 days in a secure hotel and this week added Belgium, France, Italy and Luxembourg to its list of designated states that initially also included Austria.
The EU executive wrote to the Irish Government on Friday in relation to the criteria used to determine the list, a spokesman said.
"The Commission has concerns regarding this measure in relation to the general principles of EU law, in particular proportionality and non-discrimination," the spokesman said.
"The Commission believes that the objective pursued by Ireland, which is the protection of public health during the pandemic, could be achieved by less restrictive measures."
Essential exemptions
Exemptions should also be made for essential travel, he added.
The Commission sent similar administrative letters to six other EU countries in March querying Covid-19 related travel restrictions but has yet to start an infringement process against any member state on the issue.
The Government has said that keeping new Covid-19 variants out of the country, rather than high rates of disease, is the main criteria for adding countries to the list. The Italian ambassador to Ireland also criticised the regime this week.
Ministers had flagged in advance of last week's decision that including fellow member states could be lead to issues around EU freedom of movement rules.
I make no apologies to the Commission
Health Minister Stephen Donnelly said he "flat out disagreed" with the Commission if it was telling Ireland it cannot put such measures in place for countries that have been identified as having Covid-19 variants of concern.
"I make no apologies to the Commission, to the Italian ambassador or anyone else for putting in place the measures that we believe and our public health teams believe are the right measures to keep people safe," Mr Donnelly told RTÉ television.
"We are now leading Europe by a country mile in terms of the biosecurity measures we have in place. It's something we should be very proud of and it's something the people want."
