Police at Paris' top airport lost track of a passenger's bag in which plastic explosives were placed to train bomb-sniffing dogs, police said Saturday. Warned that the bag may have gotten on any of nearly 90 flights from Charles de Gaulle (search), authorities searched planes upon arrival in Los Angeles and New York.

French police said the explosives were harmless and there was no chance of their going off, since no detanators were connected to them.

More than 300 passengers were evacuated and their luggage searched when their Air France flight from Charles de Gaulle arrived in Los Angeles late Friday the U.S. Transportation Security Administration said

Two Air France (search) and one American Airlines (search) flight to Paris were also searched in New York City, TSA spokesman Norm Brewer said. No explosives were found on any of the flights.

French police at Charles de Gaulle deliberately placed up to five ounces of plastic explosives into a passenger's luggage Friday evening, police spokesman Pierre Bouquin said.

But a "momentary lack of surveillance" led to the bag being lost on a conveyor belt carrying luggage from check-in to planes, he said.

Authorities immediately alerted the relevant airlines that one of between 80 and 90 planes that left the French capital from 5:30 p.m. to 7 p.m. Friday could be carrying the explosives, Bouquin said.

Four of the flights were en route to the United States, while others were headed to places like Japan and Brazil, Bouquin said. Some were domestic French flights. The flight searched in Los Angeles was delayed two to three hours before continuing on its next leg to Tahiti in the South Pacific.

"These dogs must be trained in the most realistic situation possible ... to be the most effective," Bouquin said.

"Indeed, it's possible that someone will have a surprise when he opens his bag."