The invention concerns an illumination system for generation of colored, especially amber or red light, comprising a radiation source and a fluorescent material comprising at least one phosphor capable of absorbing a part of light emitted by the radiation source and emitting light of wavelength different from that of the absorbed light; wherein said at least one phosphor is a amber to red emitting a rare earth metal-activated oxonitridoalumosilicate of general formula (Ca1−x−y−zSrxBayMgz)1−n(Al1−a+bBa)Si1−bN3−bOb:REn, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, 0≦a≦1, 0