The Afghan government has expressed concern to US and British officials after a mystery spraying of herbicide on opium crops in the country\'s east. The government said a probe had shown poppies in two districts of Nangarhar province had been sprayed by air without authorisation. The US and British denied any involvement in such activities. The Afghan government said villagers in Nangarhar had complained of feeling unwell after the mystery spraying two weeks ago. A local doctor, Mohammed Rafi Safi, told the AFP news agency he had treated 30 farmers who claimed their fields had been sprayed with herbicide. Presidential spokesman, Jawed Ludin, told a news conference: \"It is not just serious for us because of some health problems, it is not just serious for us because it harms the other crops, it is being taken very seriously because it affects the national integrity of our country.\" Mr Ludin said he had held talks with foreign officials to express the Afghan government\'s opposition to spraying. He said US and British officials had given the president assurances that they had \"never in the past and will never in the future support any aerial spraying either directly or indirectly\". An investigation is continuing in Nangarhar with soil samples taken from the Shinwar and Khogyani districts. Nangarhar provincial governor Din Mohammed said he was in no doubt there had been an aerial spraying. \"I don\'t know who might be behind this but... the airspace of Afghanistan is under the control of the United States,\" he said. Villager Zarawar Khan said he saw \"a huge plane flying very low\" and spraying a snow-like substance on crops. It said the country now supplied 87% of world opium. In 2003, the trade was worth $2.8bn, representing more than 60% of gross domestic product. It urged the US and Nato forces to fight drugs as well as Taleban insurgents. (BBC)