VIENNA (Deutsche Presse-Agentur) -- Drug users around the globe are increasingly turning to medicines and to new substances that are not yet banned, the UN drug control board warned Tuesday, calling on governments to fight this trend.

Abuse of prescription drugs has increased especially in North and South America, in South and South-East Asia and in some European countries, the International Narcotics Control Board (INCB) said in its annual trend report.

The Vienna-based board is especially concerned about excessive prescription and use of stimulating medicines for treating attention deficit hyperactivity disorder.

Tranquilizers are also identified as a problem. In some South American countries, more than 6 per cent of high school students take such substances.

In South Asia, people have turned to injecting prescription drugs, a trend that has helped to spread HIV and hepatitis.

INCB president Raymond Yans also warned of "legal highs" from the stream of psychoactive drugs that are being developed at a fast rate, outpacing government efforts to ban them.

"In Europe alone almost one new substance is appearing every week. Previously, between 2000 and 2005 there were an average of five notifications of new substances per year," Yans said.

The board said governments should set up early warning systems to monitor these new drugs, and they should work together more closely to prevent manufacturing and trade.

To fight prescription drug abuse, authorities should educate health workers and the public, and they should control the storage and sales of medicines more tightly, the INCB said.

The job of the UN body is to identify new drug trends and to monitor the implementation of international drug treaties.

The INCB report criticized recent successful popular votes in Colorado and Washington to legalize the recreational use of marijuana.

This development would violate international rules that allow only medical or scientific drug use, the INCB said.

It "would undermine the humanitarian aims of the drug control system, and constitute a threat to public health and well-being," it warned.

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