The ac electrical conductivity of mixed alkali LiF-KF-Al(PO3)(3) glasses has been investigated using the complex conductivity formalism. For the first time, a mixed alkali effect has been detected in the ac conductivity of glasses which also exhibit the classical mixed alkali effect in the de conductivity. The observed conductivity relaxations have been analyzed using three and four parameter functions. Jonscher's universal dielectric response yields the best description of the experimental data.