The protest is to encompass Ryanair employees in Belgium, Netherlands, Italy, Spain and Portugal.

On Thursday afternoon union leaders were due to meet the top aides of the president of the European Commission, Jean-Claude Juncker, and the commissioner for employment, social affairs, skills and labour mobility, Marianne Thyssen.

On 7 September unions across Europe representing airline cabin crew, including Portugal’s National Union of Civil Aviation Flight (SNPVAC), announced that they would call a strike at Ryanair for the end of this month.

Aside from the SNPVAC, the action later this month is to involve two Italian unions, one in Belgium, two in Spain and one in the Netherlands.

Unions are demanding that Ryanair’s employment contracts to be in line with local law in the country where staff are based, and not only the law in Ireland, which is the situation at present.

Union leaders said the strike will cause “chaos”, a claim Ryanair bosses were quick to shoot down.

In a statement sent to press rooms shortly after the strike announcement, Ryanair downplayed it, saying it "rejected false claims made by Belgian union CNE that strike action by its small minority of cabin crew on the 28th September would cause 'travel chaos'".

The airline said it expects that "even if there is another limited cabin crew strike on 28th September, the vast majority of its cabin crew across Europe will work as normal".

It also expects a "significant majority of its cabin crew in Spain, Italy, Belgium, the Netherlands and Portugal will also work normally, as they have during previous strikes", and accordingly "there will be no 'travel chaos' or 'widespread disruptions'".

Ryanair’s Kenny Jacobs said: “Repeated false claims made by these unions about “travel chaos” have proven to be unfounded. While we regret the limited strike actions that have taken place this summer, in all cases we have judiciously pre-cancelled a small number of our 2,500 daily flights in order to minimise customer disruption and inconvenience.

"We object to these lurid and inaccurate press headlines which wrongly to refer to “travel chaos”, despite the fact that during the seven days of partial strikes by a small minority of our pilots and cabin crew this summer, there has been very little disruption and absolutely no “chaos”".