The invention relates to a system (100) and method for identifying and authenticating a tag defined by at least a spatial pattern and the spectral signature of luminescent particles. The system comprises a reading module (110), a processing module (120) and a database (130) containing the stored tag identities. The spatial pattern and spectral signature are acquired by an imaging unit (111) and a spectral unit (112) respectively in a sequential manner, the acquisition being synchronized with different excitation light pulses. The validation of the tag comprises the use of background and signal acquired by both the imaging unit (111) and the spectral unit (112).