The airline said in a statement staff shortages in Greece and Spain had, by 9am, caused delays to 54 (12%) of its first wave of departures (436).

“These delays are unjustified,” said the airline. “We are sincerely regret these delays an are doing our utmost to limit their impact on flights throughout the rest of the day.”

It comes after both Ryanair boss Michael O’Leary and IAG chief executive Willie Walsh lambasted Europe’s ATC provision following industrial action.

Walsh, speaking at the Guild of Travel Management Companies (GTMC) conference last week, said the ATC “mess” was having a bigger impact on operations than fuel prices.

Walsh added he would stand alongside O’Leary in his campaign to address the ATC issue after the Ryanair boss last week said Europe’s ATC “was on the verge of meltdown”.

“Europe’s airlines are also suffering thousands of ATC delays and cancellations because of staff shortages, especially in German and UK ATC providers,” said O’Leary.

“We call on the UK and German governments, and the EU Commission, to take urgent and decisive action to ensure ATC providers are fully staffed and that overflights are not affected when national strikes take place, as they repeatedly do in France.”