Two classes of problems are considered within the framework of a general approach to solve optimisation problems with fuzzy coefficients, referred to as and models in the literature. This paper is concerned with the latter and proposes an approach which replaces the initial problem by a set of associated mutually interrelated models. To reduce the decision uncertainty region, the problem is converted to a multicriteria decision problem in a fuzzy environment using two methods. The first method reduces the region sequentially through a step-by-step comparison of alternatives. The second method analyses membership functions of a subset of non-dominated alternatives, considering all criteria simultaneously. The results have general applicability and are being used in power engineering planning in Brazil.