Health officials in Geneva have suppressed the publication of a politically sensitive analysis that confirms what ageing hippies have known for decades: cannabis is safer than alcohol or tobacco.

According to a document leaked to New Scientist, the analysis concludes not only that the amount of dope smoked worldwide does less harm to public health than drink and cigarettes, but that the same is likely to hold true even if people consumed dope on the same scale as these legal substances.

The comparison was due to appear in a report on the harmful effects of cannabis published last December by the WHO. But it was ditched at the last minute following a long and intense dispute between WHO officials, the cannabis experts who drafted the report and a group of external advisers.