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.

Authorities in Brazil said Friday they are probing Chinese auto giant BYD and one of its contractors for suspected "trafficking" of Chinese workers building a factory in the South American country.

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.