"This exchange infringes cartel law as it allows firms to adjust their market behaviour among themselves," Weko said.
Weko said the firms exchanged information concerning prices, sales, advertisement costs and general trading conditions and risked a fine if they did not stop.
It said the group was formed by the Swiss units and distributors of big luxury cosmetics makers, including Bulgari Parfums, Chanel, Coty, L'Oréal Produits de Luxe, Parfums Christian Dior, Richemont and 22 others.
ASCOPA, an industry association with 40 members representing and distributing over 180 perfume and cosmetics brands, could not immediately be reached for comment.
(Reporting by Silke Koltrowitz; Editing by Greg Mahlich)