The survey, jointly done by the U.N. Office of Drugs and Crime and the Afghan government, estimated opium poppy farmers earned more than $1.4 billion last year, or 9 percent of country's gross domestic product.
"Opium is therefore a significant part of the Afghan economy and provides considerable funding to the insurgency and fuels corruption," said Yury Fedotov, executive director of the U.N. agency.
The price increase was blamed on a supply shortage resulting from a fungal disease that wiped out the poppy crop in 2010.
About 60 percent of farmers surveyed said they were primarily motivated by the high prices from poppy cultivation. It was disturbing that the gross income from opium last year was 11 times higher than that earned from wheat, the biggest difference since 2003, officials said.
Afghanistan accounts for an estimated 90 percent of the world's opium.
The survey said poppy-crop cultivation spread over 7 percent more land than in 2010. The amount of opium produced increased by 61 percent, from 3,600 tons in 2010 to 5,800 tons last year, it said.
"The Afghan Opium Survey 2011 sends a strong message that we cannot afford to be lethargic in the face of this problem," Fedotov warned.
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