STATISTICAL EXCESS OF FOREGROUND GALAXIES AROUND HIGH-Z RADIOGALAXIES

K-band imaging of a sample of 21 radiogalaxies with z similar to 1.5 r eveals the existence of a statistical association of foreground galaxi es with the positions of the radiosources. The excess is detected with in a 1' radius at a high significance level (> 99.8%). K-band light is a good tracer of stellar mass, so this result indicates the existence of an association between foreground mass perturbations and backgroun d radiosources, as expected from the magnification bias effect, and co nfirms previous results obtained for other high-z radio-loud AGN.