  We study a non-Abelian gauge theory with a pseudo scalar coupling \phi
\epsilon ^{\mu \nu \alpha \beta} F_{\mu \nu}^a F_{\alpha \beta}^a in the case
where a constant chromo-electric, or chromo-magnetic, strength expectation
value is present. We compute the interaction potential within the framework of
gauge-invariant, path-dependent, variables formalism. While in the case of a
constant chromo-electric field strength expectation value the static potential
remains Coulombic, in the case of a constant chromo-magnetic field strength the
potential energy is the sum of a Coulombic and a linear potentials, leading to
the confinement of static charges.
