In Afghanistan, The opium production could be reduced by a quarter compared to last year's yield. The head of the UN Office on Drugs and Crime, Antonio Maria Costa told the BBC that the disease – a fungus – is thought to have infected about half of the country's poppy crop. Afghanistan produces 92% of the world's opium. Mr Costa said opium prices had gone up by around 50% in the region. That could have an impact on revenues for insurgent groups like the Taliban which have large stockpiles of opium. Mr. Costa said some local farmers believed that NATO troops were responsible for the outbreak, but he said such fungi occur naturally every few years. Four years ago there was a similar infestation.