A British scientist who received funding to begin the world's first magic mushroom depression trial has hit out at regulations which he claims have stalled his research.
David Nutt, the president of the British Neuroscience Association, was awarded a £550,000 grant from the Medical Research Council to conduct a full clinical trial on the effect of the psychedelic hallucinogen psilocybin on patients who suffer from depression.
But he said his unprecedented research had been halted because of British and European rules.
Psilocybin is illegal in Britain and is classified as a Schedule 1 drug, which means it has a high potential for abuse and no recognised medical use.
As a result, a licence must be obtained to use the drug in medical testing.
Professor Nutt, from Imperial College London, said the "primitive, old-fashioned" regulations have hindered his chances of finding a company to pay for the licence.
He told a neuroscience conference in London:
Professor Nutt's proposed trial would involve 60 patients with depression who have failed two previous treatments.
During two or three controlled sessions with a therapist, half would be given a synthetic form of psilocybin, and the other 30 a placebo.
They would have guided talking therapy to explore negative thinking and issues troubling them, and doctors would follow them up for at least a year.
Psilocybin mushrooms grow naturally around the world and have been widely used since ancient times.