In a lively Muslim quarter of Nanchang city, a sprawling Chinese factory turns out computer screens, cameras and fingerprint scanners for a supplier to international tech giants such as Apple and Lenovo. Throughout the neighborhood, women in headscarves stroll through the streets, and Arabic signs advertise halal supermarkets and noodle shops.

The U.K.-based grocery chain Tesco said it halted production at a factory in China on Sunday after a British newspaper reported the factory used forced labor to produce charity Christmas cards for the supermarket.