A 6.8 nb^-1 sample of pp collision data collected under low-luminosity conditions at √s = 7 TeV by the ATLAS detector at the Large Hadron Collider is used to study diffractive dijet production. Events containing at least two jets with p_T>20GeV are selected and analysed in terms of variables which discriminate between diffractive and non-diffractive processes. Cross sections are measured differentially in Δη^F, the size of the observable forward region of pseudorapidity which is devoid of hadronic activity, and in an estimator, ξ˜ of the fractional momentum loss of the proton assuming single diffractive dissociation (pp→pX). Model comparisons indicate a dominant non-diffractive contribution up to moderately large Δη^F and small ξ˜ with a diffractive contribution which is significant at the highest Δη^F and the lowest ξ˜. The rapidity-gap survival probability is estimated from comparisons of the data in this latter region with predictions based on diffractive parton distribution functions.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias ExactasInstituto de Física La Plata