A leak has been discovered on the Druzhba pipeline that carries crude oil from Russia to Germany, the Polish operator PERN said on Wednesday, adding that the cause was under investigation. PERN said the leak was reported late Tuesday evening on one of the two strands of the western section of the pipeline about 70 kilometres from the central Polish city of Płock. The pumps on the affected strand have been turned off but the other strand is “operating unchanged,” the statement said. Other sections of the vast pipeline network were also running normally. Emergency repair crews and the fire depar…