Electrical resistivity, magnetoresistance and magnetic susceptibility were measured for ceramic (La_1−y Pr_y)_0.7Ca_0.3MnO₃ samples (y 0.75 and 1) with different content of ¹⁸O isotope. All samples were paramagnetic insulators in the high-temperature range. Some of them became ferromagnetic (FM) metals at temperatures below 60–80 K. The high-temperature behaviour of the resistivity, magnetoresistance and magnetic susceptibility was practically identical for all samples in spite of the significant difference in their low-temperature properties. In particular, the magnetoresistance was proportional to the magnetic field squared and decreased approximately as 1/T⁵ in a wide magnetic field and temperature range. The results were interpreted based on the concept of an inhomogeneous state with pronounced FM correlations in the paramagnetic phase.