  We obtain and analyze equations determining first-order differential symmetry
operators with matrix coefficients for the Dirac equation with an external
electromagnetic potential in a $(2+1)$-dimensional Riemann (curved) spacetime.
Nonequivalent complete sets of mutually commuting symmetry operators are
classified in a $(2+1)$-dimensional Minkowski (flat) space. For each of the
sets we carry out a complete separation of variables in the Dirac equation and
find a corresponding electromagnetic potential permitting separation of
variables.
