  Some time ago Mbelek and Lachieze-Rey proposed that the discrepancy between
the results of the various measurements of Newton's constant could be explained
by introducing a gravielectric coupling between the Earth's gravitational and
magnetic fields mediated by two scalar fields. A critical assessment of this
model is performed. By calculating the static field configuration of the
relevant scalar around a nucleus in the linearised theory and then folding this
result with the mass density of the nucleus its effective gravitational mass is
determined. Considering test bodies of different materials one finds violations
of the weak equivalence principle for torsion-balance experiments which are
four orders of magnitude beyond the current experimental limit, thus rendering
the model non-viable. The method presented can be applied to generic theories
with gravielectric coupling and seems to rule out in general the explanation of
the discrepant measurements of Newton's constant by such couplings.
