In July, the consumers group gave a notice to 10 retailers over insufficient information they provided for Internet-connected gadgets.
"Faced with the lack of response or insufficient progress, the group is today summoning the two largest platforms, FNAC and Amazon, before the Tribunal de grande instance de Paris," the group said in a press release.
The organization added that it was launching the legal proceedings against the two platforms on the basis of "deceptive marketing practices" and "wrongdoing."
UFC Que Choisir stressed that the retailers had to inform consumers about such characteristics of connected objects as communication protocols, the identity of the maker, and the capacity for interoperability.
"Moreover, the nature of the personal data treated during the use of a connected object is an essential part of its activities, including the quantity of the data gathered as well as its diversity and the degree of sensitivity… The information related to the personal data of users should also be communicated to the consumer before the contract is signed, as part of the product's essential features," the organization said.
The group said that both retailers were flouting their responsibilities under the pretext of being sellers rather than manufacturers.