Speaking in Kabul, Karzai also asked local leaders to use their influence to try to end opium-poppy farming.
Meanwhile, the United States said it will double efforts against Afghanistan's drug output, focusing on both crop eradication and curbing the drug trade.
The comments come after a UN report showed this year's opium-poppy harvest to be Afghanistan's biggest ever.
The report by the UN Office On Drugs and Crime (UNODC) said Afghanistan is now producing nearly 95 percent of the world's opiates.
The UNODC also warned that opiate use in the countries neighboring Afghanistan has grown along with Afghan drug production.
(AP, AFP, Reuters)
Afghanistan's Opium Problem
OPIUM FARMING ON THE RISE Despite a nationwide program by the Afghan government to eradicate opium-poppy fields and offer farmers alternative crops, international experts say that the 2006 opium crop was as much as 50 percent larger than the previous year's record crop. Afghanistan also accounted for practically all of the world's illegal opium production.(more)