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 say workers slept on beds without mattresses, ate dirty food, and had to share one bathroom among 31 people

BYD and contractor Jinjiang Group have agreed to assist and house the 163 workers in hotels until a deal to end their contracts is reached, Brazil's Labor Prosecutor's Office said in a statement issued after meeting representatives from both firms.