  It is known that in two-dimensional relativistic Dirac systems placed in
orthogonal uniform magnetic and electric fields, the Landau levels collapse as
the applied in-plane electric field reaches a critical value $\pm E_c$. We
study this phenomenon for a distinct field configuration with in-plane constant
radial electric field. The Dirac equation for this configuration does not allow
analytical solutions in terms of known special functions. The results are
obtained by using both the WKB approximation and the exact diagonalization and
shooting methods. It is shown that the collapse occurs for positive values of
the total angular momentum quantum number, the hole (electron)-like Landau
levels collapse as the electric field reaches the value $ +(-) E_c/2$. The
investigation of the Landau level collapse in the case of gapped graphene shows
a number of distinctive features in comparison with the gapless case.
