The tunnelling current in reverse-biased Pb-p-Hg1-xCd xTe (x=0.2-0.3) Schottky barriers is investigated in a magnetic field H=0-50 kOe parallel and perpendicular to the electric field E in the temperature range T=20-250 K. The tunnelling current in magnetic fields of both orientations decreases by a factor of 10 and more. For H//E the magnitude of the effects as well as the dependence of the interband tunnelling current on magnetic field, reverse voltage (electric field), temperature and alloy composition is in good agreement with the theory. In contrast to the existing theory, for H perpendicular to E orientation the magnetic-field dependence is similar to the H//E case. No peculiarities are observed near the critical magnetic field Hcr=cE/s (s is the Kane velocity). The experimental results for H perpendicular to E may be explained qualitatively if we take into account a non-resonant scattering of light holes during tunnelling through the barrier. The scattering length estimated from the ratio of the effects in two orientations is proportional to H-1/2 and is of the order of the magnetic length, as would be expected for quantum diffusion in crossed fields.