The Jammu and Kashmir police on Monday seized 51 kg of heroin from a truck in Jammu city.A senior police officer said this is the biggest seizure of heroin by the police in J&K."Acting on specific information a 'naka' (checkpost) was set up in Narwal area of Jammu on the National Highway by-pass," the police said.A truck carrying 51 kg of heroin was stopped and the consignment costing Rs 51 crore in the international market was seized, the police said.Two locals, Ravi Kumar and Gurdeep Singh, have been arrested."The truck was coming from Handwara area of the Valley."Preliminary investigation reveals that the huge consignment had come from Afghanistan and entered the state from Pakistan-occupied Kashmir," said a police officer.