  We investigate the nature of the continuum emission and stellar populations
in the inner 1-3 kiloparsecs of a complete sample of twenty-four southern radio
galaxies, and compare the results with a control sample of eighteen non-active
early-type galaxies. Twelve of the radio galaxies are classified as
Fanaroff-Riley type I (FRI), eight as FRII and four as intermediate or
undefined type (FRx). Optical long-slit spectra are used to perform spectral
synthesis as a function of distance from the nucleus at an average sampling of
0.5-1.0kpc and quantify the relative contributions of a blue featureless
continuum and stellar population components of different ages. Our main finding
is a systematic difference between the stellar populations of the radio and
control sample galaxies: the former have a larger contribution from an
intermediate age (1Gyr) component, suggesting a connection between the present
radio activity and a starburst which occurred about 1Gyr ago. In addition, we
find a correlation between the contribution of the 1Gyr component and the radio
power, suggesting that more massive starbursts have led to more powerful radio
emission. A similar relation is found between the radio power and the mean age
of the stellar population, in the sense that stronger nuclear activity is found
in younger galaxies.
