The invention relates to a closure engageable with a filler neck having an opening and a seal seat disposed axially facing said closure, the closure having a cup-shaped body having a top and a peripheral wall, a seal for contacting the seal seat, and releasable fastening elements interacting with the filler neck. At least two fastening elements are arranged circumferentially to extend axially from the peripheral wall. Each fastening element is arranged to engage with a corresponding lock surface located on the outer periphery of the filler neck remote from and facing away from the central axis of the opening.