Italy's competition authority (AGCM) said on Wednesday it had started an investigation into luxury fashion groups Armani and Dior over the alleged exploitation of workers in their supply chain.

In a statement, AGCM said its probe focused on some companies of the Armani Group and some companies of the LVMH-controlled Dior Group, adding that it had acted in response to the actions by the Milan prosecutors.

The (Armani and Dior) companies may have made untrue ethical and social responsibility claims, in particular with regard to working conditions and compliance with legality at their suppliers

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"The (Armani and Dior) companies may have made untrue ethical and social responsibility claims, in particular with regard to working conditions and compliance with legality at their suppliers," the antitrust agency said.

They were placed under investigation "for possible unlawful conduct in the promotion and sale of articles and clothing accessories, in breach of the (Italian) Consumer Code," it added.

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Armani and LVMH did not immediately respond to requests for comment.