We have investigated the fission following a Coulomb explosion in argon clusters (up to Ar₈₀₀) irradiated by a femtosecond infrared laser with moderate intensity IL ≈13 Wcm^-2. We report the a priori surprising observation of well-defined velocity distributions of the ionized fragments Ar_n<50. This is interpreted by the formation of a valence shell excited charged ion, followed by relaxation, charge transfer by autoionizing collision at very short distance, and asymmetric fission.