Ice single crystals were deformed under torsion and dislocation arrangements were analysed by synchrotron topography at ESRF (European Synchrotron Radiation Facility). Profile analysis of topographs reveals a scale invariant character of dislocation arrangement with long-range correlations. Dislocation density gradients are shown to be slightly anti-correlated as the intensity profile is similar to an anti persistent random walk-like signal. This analysis reveals the influence of internal stresses on dislocation arrangement up to the sample scale. Similar observations on reversed torsion experiment, together with strong hardening behaviour, allow to suggest the mechanism of cross-slip of basal dislocations on prismatic planes for interpretation of local dislocation interaction behaviour.