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 rescued 163 workers living in inhumane conditions, prompting BYD to sever ties with its construction partner.

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.