The invention relates to a method for separating as a group all actinides (III), (IV), (V) and (VI) present in a highly acidic aqueous phase from fission products, particularly lanthanides also present in this phase, by means of two extracting agents operating in separate chemical domains. Uses include reprocessing of irradiated nuclear fuels, particularly to recover plutonium, neptunium, americium, curium and any trace uranium present, in a grouped but selective manner with respect to lanthanides, from an irradiated nuclear fuel dissolution solution on the downstream side of a uranium extraction cycle.