An experimental investigation was made of the influence of a controlled frequency nonreciprocity on the positions of phase resonances in ring lasers. An anomalously large shift of the phase resonances occurred as a result of a change in the frequency nonreciprocity of the resonator. It was found that an asymmetric position of a phase resonance relative to the edges of a single-wave generation zone could not be explained by an accidental frequency nonreciprocity of the laser resonator.