The B-PTP is obtained by introducing the hierarchy of decision making into the PTP ([3]), which is as follows. The decision maker at the upper level - the leader - has to organize the production so as to meet the demand at minimal production costs. His decision concerns production modes of the plants. Once he has made his decision, the decision maker at the lower level - the follower - has to organize the transportation of the products to the customers so as to achieve minimal transportation costs. The bilevel formulation of the B-PTP is now as follows: