By Jan Rocha In Sao Paulo

Chan's death has sparked public outcry in Brazil

The businessman, 46 year-old Chan Kim Chang, died after he was found unconscious with head injuries in a prison cell in the Ary Franco jail.

The guards and the prison director, who was suspended after the incident, claimed that Mr Chang had caused his own fatal injuries in a fit of rage.

Chinese diplomats have asked for the exemplary punishment of those found guilty.

Torture 'routine'

Brazil's state and federal authorities are promising rigorous investigations into the death of Mr Chang, who had dual Brazilian and Chinese nationality.

He was arrested at Rio airport for failing to declare and pay tax on $30,000.

But as more details emerge, public indignation grows.

It has now been revealed that over two months ago, the Rio authorities were alerted that torture was routinely used at the prison.

The information came from a welfare organisation which visited the prison and interviewed scores of prisoners.

But nothing was done to stop the practice.

Calls to the police hot-line have claimed that Mr Chang was tortured in order to make him reveal his credit card password.