Ryanair CEO Eddie Wilson has said Ireland is now 'last on its list' for investment going forward.
He pointed to the fact that about 8% of the carrier's traffic is in and out of Ireland.
He told The Hard Shoulder: "Over the last two months we've been making investment decisions... we've done a 10-year deal in Stansted, we've opened a base in Paris, we've opened a base in Zadar, Zagreb.
"I was on with the president of Sicily the other day, who's welcoming us with open arms - and Sicily has a population larger than Ireland.
"Ireland is the last on our list at the moment for two reasons.
"Not necessarily a date of when we're getting out of this, but what are the metrics to get us out of this in terms of infection rates, etc.
"And the second thing is put some incentive into an island nation that relies on travel in and out of here".
He also cited the success of Ireland's foreign direct investment, owing to its transport links.
"They actually attract people from all over Europe to come and work here, and they get here on Ryanair for 9.99, and that's no longer there at the moment - and no plan, no way out of this.
"We are going to take 50 years of being ahead of aviation in aviation leasing, low- fares airlines, transatlantic - we are really good at aviation in this country.
"And this Government is flushing it down the toilet at the moment".
Last May, the company announced plans to cut more than 250 jobs across several bases - including Dublin.
Government 'left holding the baby'
Mr Wilson also slammed claims by Health Minister Stephen Donnelly that airlines are not enforcing public health laws for travellers to Ireland.
Speaking on Wednesday, Minister Donnelly told Newstalk "a number of airlines" were breaking the law in relation to public health.
He said they were not enforcing the legal requirement to not let people board a plane without the pre-flight PCR, a passenger locator form or verified quarantine accommodation.
Mr Wilson said the Government is shifting the blame from itself.
"[It was] the usual sort of passing the parcel - every airline that gets a direction from the Department of Transport to do things, we all implement them.
"It didn't apply to us anyway over the last number of weeks, because it was only Austria on the [mandatory quarantine] list and we didn't have any flights from Austria.
"So he's clearly not referring to Ryanair."
He said a system of quarantine sounds good, but is not workable in a free travel area.
"Whether we like it or not, we live in the European Union and there's unrestricted, free travel within that.
"And whatever about putting in a quarantine, you can't have a quarantine with a whole in it.
"If somebody's child wants to come home from Erasmus and they're currently in France, and they have a negative PCR test, they're just going to go to Germany and fly home.
"What we have from the Minister for Health, for the last number of months, is making an announcement after not thinking anything out, not implementing anything, not asking the people on the other end of it how to implement it.
"We told them to put an online portal in place - ourselves Aer Lingus, the DAA, everyone.
"They're making these decisions in rooms and they're doing it for the benefit of opposition politicians.
"And then when they're left holding the baby, they turn around and say 'Well it must be the airlines'.
"They can't plan anything.
"When you impose things like quarantine it sounds great, but the ability to implement it in an open travel area is nonsense".
It comes as the National Civil Aviation Development Forum (NCADF) said the Government needs to identify and confirm the metrics that will justify "the removal of the ban on all non-essential international travel" for summer operations.
The group also said the EU traffic light system should be re-implemented, with different restrictions depending on different countries of origin.