A measurement of the optical absorption, induced by photon irradiation up to a dose of 0.9 MGy, in Nufern silica core single-mode optical fibres is presented. In addition, the fibres were irradiated with neutrons, up to a total fluence of 2 x 10(14) cm(-2) and the induced optical absorption was evaluated for four different wavelengths: 630, 670, 681 and 785 nm. (c) 2006 Elsevier B.V. All rights reserved.