  Magnetic properties of dirty multiband superconductors near the upper
critical field are studied. The parameter $\kappa_2$ characterizing
magnetization slope is shown to have a significant temperature variation which
is quite sensitive to the pairing interactions and relative strengths of
intraband impurity scattering. In contrast to single-band superconductors the
increase of $\kappa_2$ at low temperatures can be arbitrary large determined by
the ratio of minimal and maximal diffusion coefficients in different bands.
Temperature dependencies of $\kappa_2(T)$ in two-band MgB$_2$ and iron-based
superconductors are shown to be much more sensitive to the multiband effects
than the upper critical field $H_{c2}(T)$.
