We report two new photoluminescence systems found in Czocralski silicon doped with zinc and annealed in the temperature range C. The zero-phonon transitions of these systems are observed at 1050.31(5) meV, 1051.24(5) meV and 1100.42(5) meV. Uniaxial stress perturbations applied to these transitions reveal that both centres possess monoclinic I symmetry with almost identical stress fit parameters. These parameters are remarkably similar to those recently reported for group II acceptor and oxygen-related complexes in silicon. Defect geometries and possible perturbation mechanisms are discussed.