Chinese workers at a construction site in Brazil for a factory owned by China's electric vehicle producer BYD are victims of human trafficking, Brazilian labor authorities said on Thursday in a growing controversy in BYD's biggest overseas market.

A spokesperson for Chinese automaker BYD has objected to reports about poor conditions at a construction site in Brazil where it is building a factory, saying the allegations were aimed at “smearing” China and Chinese brands.

BYD has been building the factory with an annual capacity of producing 150,000 cars initially in Brazil, the Chinese EV giant's largest overseas market, as part of plans to start production there.