Drugs monitoring agency INCB warned in its annual report on Wednesday that designer drugs, modified to get around tight controls, are being produced in growing numbers and at a terrific pace.
"These drugs are often produced by modifying the molecular structure of illegal substances, resulting in a new product with similar effects, which then circumvents control measures," the International Narcotics Control Board said.
"Detailed instructions for the manufacture of designer drugs are often shared via the Internet," the Vienna-based UN agency also noted.
"Given the health risks posed by the abuse of designer drugs, we urge governments to adopt national control measures to prevent the manufacture, trafficking in and abuse of these substances," INCB President Hamid Ghodse said.
So far as legal drugs were concerned, the report called for greater efforts to crack down on corruption and enable better access in many parts of Africa and Asia through better legislation and education and improved distribution.
"Corruption is one of the underlying factors that makes drug trafficking possible," the INCB noted.
The report said that 90 percent of legal drugs on the market were consumed by Western countries.
But "more than 80 percent of the world's population has no or insufficient access to pain relief drugs and are suffering unnecessary pain because of it," mostly in Africa, Asia and the Americas, it added.
South Asia was now one of the main sources for traffickers of chemicals to produce synthetic drugs, the INCB noted.
Europe meanwhile made up nearly half of the world's consumption of heroin, most of it coming from Afghanistan.
Cocaine trafficking was also up again in Africa, on its way to Europe, after having fallen for two years, the report added.