Radiative transfer is of great relevance in many different physical systems, ocurring in a broad range of size scales. In some high-energy environments (e.g. gamma-ray bursts), matter can interact with radiation while being accelerated to relativistic speeds, sometimes being simultaneously subject to strong electromagnetic fields. In situations where none of these effects can be disregarded, it is convenient to rely on numerical schemes that can handle them simultaneously. Such methods must be able to resolve timescales that sometimes can differ in several orders of magnitude, which can in general cause stability issues. In this talk, I will present a numerical code applicable to radiation transfer problems in relativistic hydrodynamics and magnetohydrodynamics, designed as an independent module within the freely-distributed PLUTO code.