Disruptive air traffic controllers across Europe have been denounced by Ryanair boss Michael O’Leary with a warning that action is needed to avoid “meltdown”.

The combative chief executive of Europe’s largest airline spoke out ahead of the latest planned walkout by French air traffic controllers tomorrow (Saturday) leading to further flight cancellations.

Ryanair was forced to cancel more than 1,000 flights in May and easyJet 974 with O’Leary saying the cancellations were “almost all due to ATC staff shortages and strikes”.

The low cost carrier’s chief executive told Sky News that air traffic control staff shortages were being “covered up by ‘weather delays’ or ‘capacity restrictions'”.

“We have been told by the French authorities that we have to cancel 150 flights, many of which don’t even touch France, because the air traffic controllers there are going on strike this Saturday and Sunday,” O’Leary said.

“It’s unacceptable, and as Willie Walsh [chief executive of rival International Airlines Group] said last month, it’s getting worse.

“The real fear is that when passengers come to take their holidays in July and August, they will suffer flight cancellations, long delays or disruptions because of inadequate staffing in air control, particularly at weekends.”

A spokeswoman for UK ATC provider Nats said that its staffing issues accounted for less than 3% of cancelled Ryanair flights in the UK this year.

There was “significant weather” in southern England in April and May, including major thunderstorms which effectively blocked large swathes of airspace as aircraft can’t fly through them, she said.

“This inevitably results in delays – in effect it is very similar to closure of main roads,” the spokeswoman added.