The application describes a closeable bag or container with an elongate opening which can be closed by movement of a closure means therealong. The bag has a lock unit at one end of the opening and the closure means has a tab which cooperates with the lock unit and with a disposable locking member to close the bag or container. The lock unit has first and second apertures. The tab has at least a first aperture which can register with the first aperture of the lock unit when the tab is placed thereon. The locking member has first and second protrusions for location in the apertures of the lock unit with the tab being located between the locking member and the lock unit. At least the second protrusion of the locking member has a configuration such that it locks into the second aperture of the lock unit. The locking member has a line of weakness running between the protrusions such that the first protrusion can be disengaged from the lock unit and from the tab in a first step and the second protrusion can be disengaged from the lock unit in a second step.
