Abstract. Let G be a compact p-adic analytic group and let G be its completed group algebra with coefficient ring the p-adic integers ޚ p . We show that the augmentation ideal in G of a closed normal subgroup H of G is localisable if and only if H is finite-by-nilpotent, answering a question of Sujatha. The localisations are shown to be Auslander-regular rings with Krull and global dimensions equal to dim H. It is also shown that the minimal prime ideals and the prime radical of the ކ p -version G of G are controlled by + , where + is the largest finite normal subgroup of G. Finally, we prove a conjecture of Ardakov and Brown [1].