  We investigate the dielectric and impedance spectroscopic investigation of
Pr-doped NASICON type Na$_{3+x}$Zr$_{2-x}$Pr$_{x}$Si$_2$PO$_{\rm 12}$ ($x=$
0.05--0.2) samples as a function of temperature and frequency. The Rietveld
refinement of x-ray diffraction patterns confirms the monoclinic phase having
C2/c space groups for all the samples. The scanning electron microscopy shows
the granular-like structure and energy dispersive x-ray analysis confirms the
desired compositions. The temperature (90--400~K) and frequency (20 Hz-2 MHz)
dependence of electric permittivity are explained using Maxwell-Wagner-Sillars
(MWS) polarization and space charge polarization mechanisms. The dielectric
relaxation shows nearly equal activation energy for all the samples with a
non-Debye type of relaxation in the measured temperature range. The complex
impedance analysis shows the presence of broad grain and grain boundary
relaxation peaks. The stretched exponent analysis of electric modulus using the
Kohlrausch-Williams-Watts (KWW) function further confirms the non-Debye type of
relaxation. Moreover, scaling analysis of the electric modulus shows a similar
type of relaxation for all the samples. The {\it a.c.} conductivity data are
fitted using modified power law, where the temperature dependence of exponent
($s$) confirms the correlated barrier hopping (CBH) type conduction for all the
samples. Our results indicate that the Pr doped NASICON samples are potential
candidates for charge storage devices due to their large electric permittivity.
