Perihelion motion due to the Poynting-Robertson effect

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.