Around 40 percent of flights were cancelled at Paris Charles de Gaulle and Orly airports on just one day in January this year.

CNN: How airports beat bad weather

Paris's two main airports - Charles de Gaulle and Orly - are also operating at reduced capacity.

BBC: Snow causes more travel and school disruption

The EU study says says the problem of limited capacity is likely to worsen because many busy airports, including London Heathrow and Paris Orly, do not plan to expand.

BBC: EU Commission: Airport slots need improvement