How the UK taught interrogation techniques to Brazil's military in the 1970s
30 May 2014 Last updated at 13:07 BST
The BBC has found evidence that the UK helped teach Brazil's military dictators sophisticated interrogation techniques during the 1970s.
One document seen by BBC reporter Emily Buchanan is entitled "Torture in Brazil" and marked "confidential".
It details how the Brazilian army had introduced new interrogation techniques based on psychological methods.
This new kind of interrogation method came to be called the 'English System'.
A man who once led a Brazilian police death squad, Claudio Guerra, told Newsnight that British agents came to Brazil to teach the system.
"They said the techniques were used in Ireland and had given good results," he says.