We investigate the Abelian projection with respect to the Polyakov loop operator for SU (N ) gauge theories on the four torus. The gauge fixed A 0 is time-independent and diagonal. We construct fundamental domains for A 0 . In sectors with nonvanishing instanton number such gauge fixings are always singular. The singularities define the positions of magnetically charged monopoles, strings or walls. These magnetic defects sit on the Gribov horizon and have quantized magnetic charges. We relate their magnetic charges to the instanton number.In the absence of dynamical fermions the relevant observables for confinement studies are products of Wilson-loops [1]. At finite temperature T = 1/β the gauge potentials in the functional integral are periodic in Euclidean time i.e.and one may use Polyakov loops [2] P ( x) = tr (P(β, x)), where P(x 0 , x) = P exp ias order parameters for confinement. Below we set P(β, x) ≡ P( x). We shall follow the strategy put forward by G. 't Hooft [3] who considered Yang-Mills theories on a Euclidean space-time torus Ì 4 . The torus provides a gauge invariant infrared cut-off. Its non-trivial topology gives rise to a non-trivial structure in the space of Yang-Mills fields which yields additional information on the possible phases of Yang-Mills theories.