Multiple scattering from artificial irregularities, HF-induced in the ionospheric F region, may cause significant attenuation of both ordinary and extraordinary radio waves in addition to the anomalous absorption of ordinary waves by their conversion into plasma waves. We have confirmed the existence and detailed features of this effect at the Sura heating facility by measurements of the attenuation of the powerful pump wave and weak probing waves of extraordinary polarization. Extraordinary waves are attenuated during heating, 1.5--12 dB below a background (nonheating) attenuation value caused by scattering from natural irregularities. Irregularities involved into the multiple scattering process have geomagnetic field-transverse scales of l⊥ ~ 0.1--1 km. To determine characteristics of these irregularities, a simple inverse problem solution procedure is implemented.