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 were probing Chinese auto giant BYD and one of its contractors for suspected "trafficking" of Chinese workers who were building a factory in the

Allegations spark tensions as BYD cuts ties with contractor amid labor rights concerns, passport disputes, and China's push for stronger Brazil ties.

Brazil has stopped issuing temporary work visas for BYD , the Ministry of Foreign Affairs said on Friday, in the wake of accusations that some workers at a site owned by the Chinese electric vehicle producer had been victims of human trafficking.