Use of oligomeric or polymeric compounds having the general formula I wherein X is a halogen or or a heterocyclic radical containing in the ring at least one nitrogen atom which radical is linked to the triazine ring through one of such nitrogen atoms, R 2 is alkyl or cycloalkyl, R1 is a divalent radical of piperazine of the formula or a divalent radical of the type or n is an integer from 2 to 30, extremes included, m is an integer from 2 to 6, extremes included, p is an integer from 2 to 12, extremes included, and X1 = OH, NH2 or X whereby X and X1 may be the same or different, X 2 = Hydrogen or a C1 -C4 alkyl group as organic synergists of fire and flame retardants in self-extinguishing polymeric compositions.