Currently, the GEO population of debris objects with sizes smaller than 1 m2 - about the limit of the US Space Command catalogue - is vastly unknown. There is even evidence for an incompleteness of the catalogue at larger sizes. In view of this situation, several space agencies started to perform optical observations of the geostationary ring. NASA conducts optical surveys with a 0.32 m Schmidt telescope equipped with a CCD detector. The European Space Agency (ESA) has also initiated its own program for optical observations of space debris using a 1 m Ritchey-Chrétien telescope on Tenerife (Canary Islands). The efforts have been complemented by an initiative of the Inter-Agency Space Debris Coordination Committee (IADC). The paper presents the results from the ESA program. Most remarkable is the detection of a previously suspected substantial population of small objects. The survey sampled a limited volume of the orbital element-magnitude space only. In order to asses the observational selection effects the observations have been simulated using a reference population and the ESA PROOF tool.