  The processes $\tau^- \to \pi^- \pi^0 \nu_{\tau}$ and $e^{+}e^{-} \to \pi^{+}
\pi^{-}$ are considered within the chiral Nambu--Jona-Lasinio model with taking
into account the pion final state interactions beyond the leading $1/N_c$
approximation. The contribution of the loop correction caused by a $\rho$ meson
exchange between the pions, which gives the main contribution in the P-wave
channel, is caclulated. The results for both processes are in a satisfactory
agreement with experimental data.
