  With the Pierre Auger Observatory we have the capability of detecting
ultra-high energy neutrinos by searching for very inclined showers with a
significant electromagnetic component. In this work we discuss the
discrimination power of the instrument for earth skimming tau neutrinos with
ultra-high energies. Based on the data collected since January 2004 an upper
limit to the diffuse flux of neutrinos atEeV energies is presented and
systematic uncertainties are discussed.

Astrophysics