Hong Kong supermarkets have halted some vegetable sales amid a new food scare after pressure group Greenpeace accused grocery chains of selling produce tainted with dangerous levels of pesticides...The move followed a Greenpeace report that said vegetables at branches of Wellcome and its rival supermarket giant ParknShop had been found to contain high levels of dangerous and, in some cases, banned pesticides, among them DDT...A spokeswoman for Wellcome said the company was "concerned" by the report and had halted sales of the contaminated food and switched to alternative suppliers..."Wellcome has also issued warning letters to all vegetable suppliers..."...ParknShop quality control expert Peter Johnston told reporters the company was looking into the matter but said there was always a possibility that some food would receive more pesticide than others...adding that the contamination of samples from ParknShop were at the lower end of the scale cited by Greenpeace.