Dozens of flights to and from French airports have been cancelled today due to a general strike over French government plans to raise the retirement age.
Ryanair has listed cancelled flights on its website, including flights to and from Irish and British airports.
An Aer Lingus flight to Paris this morning, and a later flight to Nice were cancelled.
A spokeswoman for the airline said all passengers affected by the cancellations had been informed in advance. Those due to travel to Paris on the early-morning flight today would be accommodated on larger aircraft this evening.
Those due to travel to Nice would fly out tomorrow, the spokeswoman said.
The strike by French unions has shut down trains, planes, buses, underground services, post offices and schools in the dispute over raising the retirement age proposal.
The action coincided with the start of a debate in parliament over a plan to overhaul the money-losing state pension system so it will break even in 2018.
The French government insists raising the aged from 60 to 62 is essential as people are living longer, and it has urged everyone to show “courage” as it tries to chip away at the huge national debt.
The French retirement age is already among the lowest in Europe. In contrast, Germany has decided to move up the retirement age from 65 to 67 and the US social security system is gradually raising the retirement age to 67 as well.
As a large Paris march started, union leaders said that they had already mustered a nationwide turnout that topped a previous benchmark protest of two million people in June, tapping mounting unease over government austerity measures across Europe.
Government estimates also suggested higher participation, although police figures are always lower than the organisers'. The official estimate of June's turnout was 800,000.
Analysts said however that even if the unions achieved a huge turnout today, it was unlikely they could turn the day of protest into a rolling strike movement capable of forcing the government to back down.
Opinion polls show two-thirds of voters think Mr Sarkozy's plan to raise the retirement age is unfair and support the protest, but two-thirds also think the strikes will make no difference.
The strikes cut rail services by 50 per cent or more but international links were mostly unscathed. Urban underground train services were also hit, though somewhat less than feared.
Civil aviation authorities asked airlines to cancel a quarter of their flights at Paris’ airports.
The labour unrest mirrors action in other European countries against austerity measures. Governments in Greece, Spain, Italy and Romania have so far faced down strikes to impose painful pay and public spending cuts. London's underground rail network was paralysed today by a 24-hour strike against job cuts.
The French strikes mostly targeted the public sector but several hundred steel workers downed tools at an Arcelor Mittal plant in northeastern France to highlight how the reform might worsen the plight of people with particularly gruelling jobs.
Additional reporting: PA/Reuters