PARIS — France’s civil aviation authority asked airlines to reduce flights by 40% at Paris-Orly airport on Sunday evening after air traffic control systems suffered a breakdown.

The authority, known as DGAC, said in a statement that some “regulation” was needed involving a significant reduction in the number of flights. The statement didn’t provide details on the cause of the breakdown.

DGAC said its teams “are fully mobilized to restore normal operations as soon as possible.”

Paris-Orly airport serves domestic and international flights, including to most European countries and the U.S.

Flights to Spain, Denmark, Saudi Arabia, Italy, Germany, Austria, the Netherlands, Ireland and several French cities were canceled on Sunday while many others were delayed.

More than 33 million passengers traveled through Paris-Orly airport last year, about half the number at Paris-Charles-de-Gaulle, according to figures released by the operator Aeroport de Paris.