By Fabio Teixeira RIO DE JANEIRO/SHANGHAI (Reuters) -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.

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.

Brazilian labor authorities have accused Chinese electric vehicle company BYD and its contractor, Jinjiang Group, of human trafficking at a construction site in Bahia. The allegations highlight challenges in China's investment model and its relations with Brazil as BYD seeks to expand globally.