Long the traditional source of opium used for making heroin, the so-called Golden Triangle could become a minor source of the poppy in the next few years.
Afghanistan has taken its place.
A UN report on illegal drugs, made public on Wednesday, provides both good news and bad news. Declining use or production in some areas is countered by new markets elsewhere or new centers of production or trafficking, including North Korea.
The report, released in Paris by the UN Office on Drugs and Crime, showed that nearly 200 million people around the world used illegal drugs in 2000-2001.
"Globally, cocaine is the problem of the Americas, heroin is the problem of Asia and cannabis is the problem of Africa," the agency's executive director, Antonio Maria Costa, said.
Cannabis "continues to be the most widely produced, trafficked and consumed illicit drug worldwide," with nearly 163 million people using it, according to the UN report.
Cocaine use remains a problem but production decreased for the second straight year.
Heroin production increased despite a "major reduction in poppy cultivation" in the Golden Triangle area in southeast Asia, where Myanmar, Thailand and Laos meet.
A 16 percent increase in poppy cultivation between 1998-2002 in southwest Asia comes mainly from Afghanistan, which produces 76 percent of the world's opium.
"The price of a gram of heroin in Afghanistan is between is between US$1 and US$5, while it sells for nearly US$100 in Europe," Costa said.
Costa said earlier this month that war and lawlessness have fed the surge in poppy production in Afghanistan, helping the drug economy to thrive.
Marijuana production also appears to be increasing. However, in the US, use fell in 2002 among high school students, almost 10 percent less than in 1997 and some 30 percent less than in the late 1970s, the report said.
The number of people around the world who abuse opium and heroin has also remained stable at about 15 million. Opium, derived from the poppy plant, is a narcotic that can be smoked on its own and serves as the main ingredient in heroin.
But decreases in Western Europe have been countered by growing markets in East Europe, Russia and Central Asia.
Also increasing is intravenous heroin abuse, which, through addicts sharing used needles, is causing AIDS to expand at an alarming rate, the report says.
A drop in demand in Australia, where trafficking networks were being dismantled, was apparently being compensated by heroin "originating in, or being trafficked" via North Korea, according to the report.
Cocaine is abused by about 14 million people, with the US the world's largest cocaine market. Two of the three main suppliers, Bolivia and Peru, are both successfully reducing coca production.
The number of cocaine users in the US has stabilized, with some 15 percent less using in 2002 than in 1998, and 60 percent less than in 1985, according to the report.
Production of synthetic drugs, often made with easily available chemicals in concealed laboratories, is hard to track.
Amphetamine-type stimulants like Ecstasy, known as ATS, represent an expanding market, particularly in the US, the report said, based on the number of seizures of labs and end-products and consumption reports.
However, the market is changing, and trafficking is shifting toward east Asia and southeast Asia. North Korea is "emerging as a significant source-transshipment area for methamphetamine going to Japan," the most lucrative market in the region.