The experiments in Rawalpindi were part of a much larger project intended to test the effects of chemical weapons on humans.
More than 20,000 British servicemen were subjected to chemical warfare trials between 1916 and 1989 at the Defence Ministry's Porton Down research centre in southwest England.
According to documents at The National Archives in London, British scientists and doctors tested the effects of mustard gas on hundreds of Indian soldiers[3] over a ten-year period.
The exact place where the British facility equipped with gas chambers was located in Rawalpindi is unknown.
Porton Down officials have argued that trials took place in a different era, during a conflict, and so their conduct should not be judged by today's standards.