"Dr Gordon Macdonald, chief executive of the alliance Care Not Killing, said: 'The development of personal gas chambers marks a new low in the debate about whether or not to kill people via assisted suicide and euthanasia.
"'What is equally risible is the claim that these will give people a quick pain free death, as this was exactly what was said about the use of death row drugs in the handful of places that have introduced assisted suicide or euthanasia.'"