Ryanair said its group passenger numbers for June fell by 97% as Covid-19 airspace closures continued to hit the airline industry.
The airline said it carried just 400,000 passengers last month compared to 14.2 million the same time last year.
Ryanair operated just over 2,800 scheduled flights in June compared to 79,600 it had budgeted for.
The airline yesterday resumed operating 40% of its schedule, as it attempted to get passengers moving around Europe again in higher numbers.
The company plans to have more than 1,000 daily flights operating across its network, restoring services on 90% of its routes.
However, the development comes amid an intense debate in Ireland about whether people should or should not take summer holidays abroad, as fears rise that it could lead to additional cases of Covid-19 being imported into the country.
Health Minister Stephen Donnelly said he will bring a recommendation on international travel to cabinet on Monday amid warnings from top health officials that a resumption of non-essential travel could reignite the coronavirus crisis.
The outgoing government last week promised to produce a "green list" by July 9 of countries for which a 14-day quarantine would not apply.
But new Taoiseach Micheal Martin and Halth Minister Stephen Donnelly have said they will take a cautious approach.
"July 9 is a decision that has been taken to publish a list. There may be a recommendation to cabinet that that might change," Stephen Donnelly said today.