French sports daily L`Equipe`s website carried a picture of Muffat holding her Olympic gold medal along with the words "French Sport in Mourning."
French President Francois Hollande spoke of his "immense sadness," while some of the country`s best-known athletes offered their condolences.
The helicopters apparently collided in midair near Villa Castelli in La Rioja province, about 730 miles (1,170 kilometers) northwest of Buenos Aires.
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