  The CP-violating phases in the soft supersymmetry-breaking sector in orbifold
compactifications with a continuous Wilson line are investigated. In this case
the modular symmetry is the Siegel modular group $Sp(4,Z)$ of genus two. In
particular, we study the case that the hidden sector non-perturbative
superpotential is determined by the Igusa cusp form ${\cal C}_{12}$ of modular
weight 12. The effect of large non-perturbative corrections to the dilaton
K\"ahler potential on the resulting CP-violating phases is also investigated.
