A locking assembly (30) for securing a rod (20) in a receiving (5) part of a bone anchoring device (1) for use in spinal or trauma surgery is provided, said locking assembly including: a first locking element (31) having a first end and a second end and a longitudinal axis of rotation and a substantially cylindrical outer surface provided with an external thread (35), a coaxial bore (36) passing entirely through said first locking element and an internal thread provided at said bore, a second locking element (32) having a longitudinal axis of rotation and a substantially cylindrical outer surface with an external thread cooperating with the internal thread of said first locking element, characterized in that said first locking element (31) has a recess (37) extending from the first end in the direction of the second end, said recess defining a circumferentially closed wall portion, wherein the interior of the wall portion has a longitudinally extending structure (38) for engagement with a tool. Furthermore, a tool (50) is provided which has sections (54,56) which can be independently engaged with the first and second locking element, respectively..
