Normal automorphisms of a soluble product of abelian groups

Let G be a soluble product of class n a parts per thousand yen 2 of nontrivial free abelian groups. We prove that the subgroup of all automorphisms of G identical on the last nonunit commutant G ((n)), coincides with the subgroup of all inner automorphisms corresponding to the elements of G ((n)). We also show that the subgroup of all normal automorphisms of G coincides with the subgroup of all inner automorphisms.