We have used three large-scale radio surveys to study the spectral behaviour of radio sources towards Abell clusters of galaxies. Without attempting to separate genuine cluster sources from background sources, we find a steeper median spectral index within 0.5 Abell radii (r_A_) than between 0.5 and 1 r_A_ (1 r_A_=3 h_50^-1 Mpc, and H_0 = 50 h_50_ km/s/Mpc). Removal of sources with extreme spectral indices yields a high probability for the presence of a correlation (within 1 r_A_) between projected distance from the cluster centre and source spectral index. This precludes a previous conjecture that the trend may be due to a few very steep spectrum sources only. Restriction to stronger sources improves the correlation and increases its slope, suggesting these sources to be more likely associated with cluster members.