"Some obvious problems remain, like opium in the south of Afghanistan, a cancer that threatens security and health and breeds corruption," said UNODC executive director Antonio Maria Costa, ahead of Tuesday's publication of the 2007 World Drug Report.

"Furthermore, progress made in some countries is being offset by negative trends elsewhere," he said.

"It is also hard to be conclusive about the drug situation in some of the worlds biggest and fastest growing countries because of a lack of data," he added.

"Nevertheless, from a global perspective, the problem seems to be contained. In the past few years, the world drug situation has stabilized. There is some ground for optimism that the run-away train of drug addiction is being slowed down."

Costa warned against complacency, however, saying that the drug problem had not been solved.

"Drugs remain a deadly form of addiction, pose a real danger to security and health, and are ruining the lives of millions of people worldwide. There is still much work to be done," he said.

Further support was needed to reduce the vulnerability of farmers to the temptation of illicit incomes.

Further improvements were also needed in drug law enforcement -- particularly through regional cooperation -- to stop the drug producers and traffickers.

The highest priorities in the fight against drugs should be prevention, helping people free themselves from drug dependence, and getting them back into society, he said.