Optical plasma diagnostic systems often require a complex optical path involving mirrors, lenses and windows. The use of optical fibres could significantly simplify the design of such a system. Radiation-induced effects, namely induced absorption and luminescence, may compromise the integration of optical fibres in the diagnostic system. However, recent developments of new fused silica glass types open perspectives to use optical fibres as a wave-guide device. In this paper, we present the common European, Japanese and Russian efforts in setting up a standardized round-robin procedure to test the optical fibres under relevant ITER conditions. The round-robin procedure should allow to select the most appropriate optical fibre. We briefly illustrate the discussion with results of an in-core reactor irradiation of pure silica optical fibres in the BR2 material testing reactor of the Belgian Nuclear Energy Research Centre.