Striking French air traffic controllers forced airlines to scale back departures from Paris today, causing chaos at the capital's airports and stranding families during school holidays.

Unions called a five-day strike starting today to protest against a deal on modernising air traffic control, signed by Germany, Belgium, France, Luxembourg, the Netherlands and Switzerland. Unions fear the reforms will lead to layoffs.

Half of the short- and medium-haul flights at Orly airport and a quarter of similar flights at Charles de Gaulle airport were cancelled on Tuesday, a spokesman for civil aviation agency DGAC said.

Traffic disruption is expected to continue until Saturday morning. Air France has said none of its long-haul flights will be affected.

Families with children waiting at the Paris airports for news on cancelled flights expressed anger, saying they were being held hostage by the labour dispute, television footage showed.

French unions are also protesting against expected budget cuts in 2010 and 2011 as part of a broader government effort to rein in spending.