Ryanair has cancelled four flights to and from Dublin this morning due to a strike by French air traffic controllers while Aer Lingus has also warned passengers to expect delays.

Flights FR6875 to Barcelona, FR1116 to Reus Salou, FR7256 to Madrid and FR7032 to Faro were cancelled at 9.30am. Flights from Barcelona (FR6874) and Faro (FR7033) into Dublin have also been cancelled.

Delays and possible further cancellations are expected and passengers are advised to check the airline's website for updates.

Another 26 flights to and from France have been cancelled, none of which are to or from Irish airports.

The strike is affecting flights to and from France and those flying through French airspace. Today is the start of a six-day strike by the air traffic controllers.

Aer Lingus plans to operate a full schedule flights today but has warned passengers to expect delays. Updated flight information is available on the airline's website.

France’s civil aviation authority has estimated that three-quarters of flights will operate during the strike, with one in five flights to Spain, Portugal, Morocco, Tunisia and Algeria on schedule.

It asked airlines to cut flights by 20 per cent in airports in southern France to ease the pressure.

The strikers, who are attached to the Unsa-ICNA union, are protesting against planned cuts that they say would harm air traffic control services in France.

Ryanair called on the European Commission to remove the right to strike from Europe's air traffic controllers, who it said were "attempting to blackmail ordinary consumers with strikes".

The company said many of Europe’s police forces and army personnel were not allowed to strike. Nor were air traffic controllers in the United States, “meaning the skies over the US cannot be closed or severely disrupted by air traffic control strikes or work to rule”.

Ryanair said flights to, from or overflying France tomorrow may also be subject to delays or cancellation. It apologised for any delays or inconvenience.