Handbags, wallets and clothes have been found in house searches of workshops in Italy where Chinese migrants have worked under substandard conditions, documents seen by the AFP news agency show.
A total of 13 brands have been asked to report their supply chains. However, none of the companies are yet under any formal investigation.
In addition to Gucci, Prada and Versace, the brands include Yves Saint Laurent, Givenchy, Dolce & Gabbana, Missoni and Adidas.
In addition, Dior's subsidiaries Manufactures Dior and Giorgio Armani Operations are also being investigated.
Companies are reportedly outsourcing work to subcontractors, who in turn subcontract it to others. This is happening at a time of poor oversight of working conditions and tighter margins for companies, writes AFP.
