Ireland has been criticised for its "particularly repressive" mandatory hotel quarantine regime by Willie Walsh, the director general of the International Air Transport Association.
Mr Walsh, a former CEO of IAG, which owns Aer Lingus and British Airways, said the State's restrictions were "particulary dangerous for a country like Ireland. The message is we don't want people travelling to the country."
"Freedom of movement is a fundamental principal of the EU. That is what has upset me most."
Mr Walsh said Ireland had mandatory hotel quarantine for 70 countries.
"Nobody travelling into the UK from Belgium tested positive yet you are locking them up," he said.
He questioned Ireland's policy of imposing mandatory hotel quarantine on vaccinated travellers.
"If these people are vaccinated then these restrictions should be removed. Why do you want to lock up people who have been fully vaccinated?"
He said it would take several years for the international aviation industry to recover to 2019 levels - partly due to aircraft being retired.
Mr Walsh said the most challenging period facing airlines will be as they try to resume business and they begin to use cash quickly.
He told the Oireachtas Transport Committee that it was "very regrettable" that Aer Lingus had to shut its cabin crew base in Shannon.
He added it was caused by the lack of transatlantic travel and said he did not see any way for Aer Lingus to avoid the decision.
Mr Walsh said he did not see how Aer Lingus could guarantee the operation of a transatlantic base in Shannon this summer because there would be few flights to the US for a second year in a row.
Fianna Fáil TD Cathel Crowe has described the decision by Aer Lingus as "devastating" for the Shannon area.
He added "practically all of the Aer Lingus wage bill is being paid for by the Government and Government has skin in the game here."
Meanwhile, Fianna Fáil's transport spokesperson Senator Timmy Dooley said the mandatory hotel quarantine system "is acting as a deterrent to a plan to recover the aviation sector".
Speaking on RTÉ's Today with Claire Byrne, he said while a credible recovery plan for the aviation sector has been talked about, it has not really been in place.
This is not about getting aviation up and running again, he said, "it's about getting our economy back to some level of normality".