The invention relates to an assembly which includes: two rotationally symmetrical components (10, 20) for supporting the blades of a turbine engine, arranged one inside the other concentrically about a turbine engine axis, and a system (30) for locking the components (10, 20) such as to prevent the relative translation of same in the axial and radial directions relative to said axis, the system including a slotted ring (40) comprising a U-shaped cross-section suitable for receiving one end of the components (10, 20), the assembly being characterised in that the ring (40) and one of the components (10, 20) are shaped such as to allow the ring to be interlocked on the component, and in that the locking system (30) also includes a member for stopping the rotation of the ring relative to the component with which the latter is interlocked. The invention further relates to a method for assembling such an assembly.