Temperature variation of electrical resistivity, thermopower and electron spin resonance measurements have been carried out in Pr (1-x)SrxMnO3 (x = 0.2, 0.26 and 0.3) in order to study the influence of carrier concentration on the formation of spin clusters in the paramagnetic state. Activation energies obtained from resistivity and thermopower was seen to behave in the opposite trend to that obtained from ESR linewidth and intensity with respect to variation in 'x', the carrier concentration, implying that the origin of these energies are different from each other. It is seen that spin clusters exist in the paramagnetic state even in a ferromagnetic insulating composition namely x = 0.2, where the double exchange strength is the weakest. © 2007 Elsevier B.V. All rights reserved.