The United Nations says Afghanistan has a monopoly on illegal opium production.
According to the UN Office on Drugs and Crime, the global
opium market is worth $US65 billion per year.
The agency says this funds global terrorism, caters to 15 million addicts and kills 100,000 people every year.
Afghanistan produces 92% of the world's opium, with the equivalent of 3500 tonnes leaving the country each year.
Most of the opium that leaves Afghanistan makes its way to Europe and other markets through Pakistan, Central Asia and Iran.
UNODC says more people die globally from Afghan opium than any other drug. But only 2% of what is produced is seized en route.
However, the agency says Iran intercepts about 20% of the opium entering its territory and Pakistan 17% - but Russia and some European countries are seizing less than 5%.
The BBC reports one gram of heroin worth $US3 in Kabul is estimated to be worth up to $US100 on the streets of London, Milan or Moscow.
Huge stockpile suspected
The UNODC also says there is a pressing need to locate and destroy massive stockpiles of Afghan opium. The agency believes an estimated 12,000 tons is being hoarded.