They said the sugar-cane cutters had been lured from the poor north-eastern region of Brazil with false promises and then made to work as bonded labour.

They had little to eat and some shacks where they lived had no ventilation.

Brazil recently became the first country in the world to recognise it had a problem of modern-day slavery, but cases in the more developed south of the country are comparatively rare.

President Luiz Inacio Lula da Silva has committed the government to eliminating the problem for good.