The contribution is focused on solution of the kinematic limit analysis problem within associative perfect plasticity. It is a constrained minimization problem describing a collapse state of an investigated body. Two different penalization methods are presented and interpreted as the truncation method and the indirect incremental method, respectively. It is shown that both methods are meaningful even within the continuous setting of the problem. Convergence with respect to penalty and discretization parameters is discussed. The indirect incremental method can be simply implemented within current elastoplastic codes.