Passenger traffic at Paris airports slid 0.6 percent last month, the first year-on-year drop since December 2010, dragged down by declines on international routes to North America and short-haul services within France, ADP said on Friday.
European traffic excluding France was almost flat, up just 0.1 percent, while traffic within France fell 4.6 percent, the operator of Charles de Gaulle and Orly airports said in a statement.
"The presidential elections and the presence of public holidays in midweek have 'blocked' some leisure traffic," ADP said. "Traffic has also been affected by a tough comparable base from last year as traffic was up by 4.4 percent in May 2011."
Traffic to and from North America fell 5.4 percent. This followed a "sharp reduction in capacity of flights offered by some airlines", ADP said.
Overall, international traffic excluding Europe inched 0.5 percent higher, helped by increases of around 5 percent on Asia-Pacific and Middle East routes, ADP added.
Traffic through ADP's Paris terminals rose 2.2 percent in the first five months of the year to 34.8 million passengers. The total last month was 7.6 million.
Fraport, the operator of rival European hub Frankfurt, said on Thursday passenger traffic at Germany's biggest airport rose 1.4 percent last month to 5.1 million, helped in part by football fans flying east for the Euro 2012 tournament.