A treatment of neutrino transport in stellar interiors is presented. The method is displayed in the framework of the Lorentz bifluid approximation, retaining only coherent scattering on heavy nuclei. The method allows a complete and consistent determination of the time dependent neutrino distribution function, valid in all regimes including the semi-transparent one, without introducing flux-limiting schemes. This deals with the angular dependence of the distribution function (it incorporates the natural closure relationship for the Eddington moments), and with possible strong discontinuities in the scattering medium. Finally, a simulation of the neutrino flow in the collapsing core of a supernova, followed up to trapping, is presented, before we discuss the adaptation of the method to neutrino production by electron capture and neutrino thermalisation by scattering on light particles.