Direct and inverse problems for leak identification in long distance gas pipelines in stationary operational modes on the base of data obtained by pressure monitoring in pipeline’s inlet, outlet and in several intermediate check points have been formulated. Algorithms for solving of the formulated problems have been developed and their numerical study has been done. On this basis methods for leak detecting, its intensity and location determination with the use of the data of pressure monitoring have been suggested. Quantitative evaluation of precisions of the proposed methods has been conducted.