Comment on 'Evolution of the unidirectional electromagnetic pulses in an anisotropic two-level medium'

Recently, Zabolotskii [Phys. Rev. E 77, 036603 (2008)] presented the Lax pair for a version of the reduced Maxwell--Bloch equations. This version was derived under considering the unidirectional propagation of a two-component electromagnetic pulse through an anisotropic two-level medium. We demonstrate that his derivation contains essential omission, which led to the wrong version of the reduced Maxwell--Bloch equations. We also point out that the Lax pair for correct version of these equations had been known in the most general anisotropic case.