The anomalous behaviour of the temperature dependence of the electrical resistivity in Pu-based dilute alloys (δ-Pu) has been considered within the Mott two-band conductivity model. It has been shown that the physical origin of the negative sign of the temperature coefficient of resistivity (TCR), observed in δ-Pu based alloys, is the interference between electron-impurity and electron-phonon interactions. A simple criterion for negative TCR observability at high temperatures (T>D) was found and applied to explain qualitatively the experimental data on the TCR in some Pu-based dilute alloys. To make a numerical evaluation of the electrical resistivity, the coherent potential approach to the Mott two-band conductivity model was combined with the ab initio obtained fcc-Pu density of states (as the starting point in the iteration procedure) and applied to the calculation of resistivity temperature dependence in pure Pu and Pu-5 at.% Al alloy. The results are compared with experimental data.