In this paper, magnitude and phase components of excitation source information are explored for language identification (LID) study. The linear prediction (LP) residual of speech signal represents the excitation source information. The magnitude and phase components of LP residual are processed individually at sub-segmental, segmental and supra-segmental levels. Evidences from both magnitude and phase components of LP residual are combined to capture the language-specific excitation source information. The LID studies are carried out on IITKGP-MLILSC speech database. The segmental level information yields better performance compared to sub-segmental and supra-segmental level information. The combined evidences from three levels represent the excitation source information. This study shows that, both magnitude and phase of LP residual contains significant language-specific excitation source information. From the LID performances of this study, it is observed that the phase component of LP residual contains more language discriminative information than the magnitude component of LP residual. © 2013 IEEE.