[en] The elastic scattering angular distributions for the weakly bound nuclei "6Li and "7Li on "6"4Zn were measured in a wide angular range at energies around the Coulomb barrier. In addition, the excitation functions of quasi-elastic scattering at backward angles were measured and the corresponding barrier distributions were derived. The experimental data were analysed within the continuum-discretized-coupled-channel method. In this contribution, we will present a detailed study concerning the effects of the break-up channels in the "6","7Li +"6"4 Zn reactions. (paper)