The invention relates to a stopping device (20) for a container (1) with a neck (12), said device comprising a stopper (21) and a plastic cap (24) that can cover both the neck and the stopper positioned in the neck. The cap (24) comprises a cover (26) and a ring (25) that is suitable for surrounding the stopper (21) and the neck (12) when mounted and provided with means (253) for locking onto the neck. The ring (25) and the cover (26) are produced as a single component and are connected by at least one part that is breakable by means of a force parallel to a central axis (X25) of the ring and directed towards the stopper (21). The cover (26) is provided with an element (262) for resting against the stopper (21). The breakable part consists of bridges (27) extending radially between an outer radial edge (261) of the cover (26) and an inner radial edge (257) of the ring (25). A channel (28) in an arc of a circle is defined between two adjacent bridges (27), the length of the outer radial edge (261) of the cover and the length of the inner radial edge (257) of the ring. Said channel has a radial width (28) of less than 0.3 mm and an axial height (H28) of more than 0.15 mm.
