Abstract: The invention relates to a closure system for containers comprising a threaded plug (1) and the neck (3) of the container (2) or the similar embodied in the form of an pouring aperture (5), the threaded plug being screwed on the neck in such a way that said pouring aperture is closed. The inventive closure system for containers is characterised in that it is embodied in the form a single-use closure system which comprises an extensible flange (15) arranged at the level of the threaded plug in the back clamping area of the flange (7) of the neck (3) embodied for this purpose. The external radial size of said extensible flange is greater than the radial dimension of a hole defining the back clamping area of the flange. The extensible flange can, for example be engaged in the pouring aperture (5) of the neck (3), and the back clamping zone (7) can be provided in a pouring passage (4) in a neck part.