UNITED NATIONS (CNN) -- The United Nations is calling on NATO to do more to stop the Afghan opium trade after a new survey showed how the drug dominates Afghanistan's economy.



Afghan villagers tend to opium poppies in Taliban-controlled Helmand province in April 2007.



The report from the U.N.'s Office on Drugs and Crime shows the export value of this year's poppy harvest stood at around $4 billion, a 29 per cent increase over 2006.



Despite Afghan security forces' efforts to curb the trade, 660 tons of heroin and morphine were trafficked out of the country in 2007, the report said.



Opium is derived from poppies, and the data on cultivation was collected by examining satellite images and by assessments on the ground.



The report said opium has accounted for more than half of Afghanistan's gross domestic product in 2007. InvestorWords.com defines GDP as the total market value of all final goods and services produced within a country in a given period of time, usually a calendar year.



According to the U.N. survey, about a quarter of the earnings from opium go to farmers. The rest goes to district officials who collect taxes on the crop, to drug traffickers and to the insurgents and warlords who control the trade.



Antonio Maria Costa, executive director of the U.N. Office on Drugs and Crime, urged NATO to take a more active role in countering the spread of the drug trade, which has increased dramatically since the American-led invasion to remove the hard-line Islamist government of the Taliban in October 2001.



"Since drugs are funding the insurgency, NATO has a self-interest in supporting Afghan forces in destroying drug labs, markets and convoys," Costa said in a written statement to coincide with the release of the survey. "Destroy the drug trade and you cut off the Taliban's main funding source."



James Appathurai, a NATO spokesman, said coalition forces were equally concerned by the rapid growth in the narcotics trade.



"We share the U.N.'s concerns," Appathurai told CNN. "Drugs not only poison people, but they poison economies and governments, and it is in everyone's interest to stop this proliferation."



He said NATO forces were providing assistance to Afghan police through training and transport but he said there were no plans to deploy coalition troops to intervene directly.



"The issue of whether we can do more is certainly a live discussion for NATO, but at the moment this is a matter for the Afghan government," Appathurai said.



Farming of opium poppies has been almost eradicated in the north and west of the country, Appathurai said.



However, he said, in the lawless southern provinces and especially in the Taliban stronghold of Helmand, poppy production was going on largely unchecked.



According to the report, U.N. observers have noticed a proliferation of heroin labs in neighboring countries and along trafficking routes.



Costa said the labs are dependent on precursor chemicals, like acetic anhydride, that must be smuggled into the region.



He called for tighter controls in chemical-producing countries and stronger intelligence-sharing between Afghanistan and its neighbors.



"Drug trafficking is a transnational threat, and therefore national initiatives have their limitations," the U.N. drug chief said.



Appathurai said the most effective way to curb the drug trade was tackling the insurgency head-on. He also said it was important to provide alternative work for poor Afghan farmers to encourage them to give up opium production.



"You cannot have eradication in isolation. If we don't give them the support to produce alternative crops, then by wiping out their opium fields, you are only creating enemies for the future," he said. E-mail to a friend
What makes up half of Afghanistan's GDP? What does UN chief advocate? What does the U.N. drug chief advocate?
The report said opium has accounted for more than half of Afghanistan's gross domestic product do more to stop the Afghan opium trade NATO to take a more active role in countering the spread of the
question: What makes up half of Afghanistan's GDP?, answer: The report said opium has accounted for more than half of Afghanistan's gross domestic product | question: What does UN chief advocate?, answer: do more to stop the Afghan opium trade | question: What does the U.N. drug chief advocate?, answer: NATO to take a more active role in countering the spread of the