Silica-based glasses doped with Yb2O3 and combination of La2O3 and Yb2O3 were synthesized. Ag+ ions were introduced in the glass through Na+ -Ag+ ion exchange, further heat treatment of the glass samples initiates the formation of luminescent silver clusters. Glass samples show typical white luminescence of silver clusters as well as sensitized luminescence of Yb3+ ions under UV excitation. Introduction of Yb3+ ions into the glass decreases quantum yield and lifetime of silver cluster luminescence indicating the presence of energy transfer. While phosphorescence lifetime decreases gradually with increase in Yb3+ concentration, fluorescence lifetime shows only a minor decrease for the highest Yb2O3 content. Additionally, decrease in quantum yield is much higher than that of emission lifetime suggesting the coexistence of two different quenching mechanisms.