The United Nations says the price of Afghan opium rose dramatically in 2011.
Yury Fedotov, executive director of the UN’s Office on Drugs and Crime, said in a statement that "opium is therefore a significant part of the Afghan economy and provides considerable funding to the insurgency and fuels corruption."
According to the UN, farmer income derived from Afghanistan's opium crop in 2011 was $1.4 billion, representing 9 percent of GDP.
The overall opium crop increased by 61 percent, from 3,600 tons in 2010 to 5,800 tons in 2011.
The value of the opium yield rose 133 percent from 2010, when plant diseases killed much of the Afghan crop.
Afghanistan grows about 90 percent of the world's opium.
Last year opium generated 11 times more revenue for Afghan farmers than wheat.
compiled from agency reports