  We study nonlinear transport through a classical ballistic system accounting
for the Coulomb interaction between electrons. The joint effect of the applied
bias $V$ and magnetic field $H$ on the electron trajectories results in a
component of the non-linear current $I(V,H)$ which lacks the $H\to -H$
symmetry: $\delta I=\alpha_{cl} V^2 H$. At zero temperature the magnitude of
$\alpha_{cl}$ is of the same order as that arising from the quantum
interference mechanism. At higher temperatures the classical mechanism is
expected to dominate due to its relatively weak temperature dependence.
