Abstract: Filter cigarettes which are grouped in the form of one or more rows on their way to the draping station or stations of a packing machine are transported sideways past a testing station between two testing units each of which has a discrete detector for each row of cigarettes in a group. Each detector has a source of light, a photoelectric transducer, and a bundle of fiber optics which convey light beams from the source against the respective end faces of cigarettes advancing between the two testing units and which convey reflected light to the respective transducer so that the latter generates signals denoting the characteristics, the presence or absence of cigarettes. Such signals are compared with a reference signal denoting the characteristics of satisfactory cigarettes, and the groups wherein one or more cigarettes have caused the generation of signals deviating excessively from the reference signal are expelled from the conveyor prior to reaching the first draping station of the packing machine.