Two southern Afghan provinces -- Helmand and Oruzgan, where the Taliban has been most active -- are responsible for the bulk of the increase.
In a statement, John Walters, the director of the White House Office of National Drug Control Policy, said the booming drug industry poses a threat to Afghanistan's internal stability. He said "increased emphasis and continued reductions are necessary" to reduce the country's drug trade.
The news is a setback for U.S. and NATO efforts to clamp down on the country's illegal drug industry.
It's also seen as a boost to the resurgent Taliban, which is accused by U.S. officials of using proceeds from drug sales to buy weapons and attract new recruits.
Meanwhile, suspected Taliban militants have killed four Afghan road workers whom they accused of spying for U.S. forces in eastern Afghanistan.
Afghan police said the men were working on a U.S.-sponsored road construction project in eastern Kunar Province.
They were kidnapped nearly two weeks ago, and their bodies were found on a mountain today. A purported Taliban spokesman, Mohammad Hanif, claimed the killings on behalf of the Taliban and said the men were spying for U.S. forces.
RFE/RL Afghanistan Report
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