  The force acting on a test particle moving around a body that is gravitating
and emitting electromagnetic radiation at the same time is computed up to the
second order in $1/c$, and the shift of perihelion is found. The total shift is
positive (the perihelion moves in the direction of particle revolution) and it
increases from zero to infinity as the radiation pressure to gravity ratio
increases from zero to 1. The additional shift caused by the radiation pressure
contains a term inversely proportional to eccentricity, therefore it may
dominate over the general relativistic shift if the orbit is round enough.
