Tamperproof closures for use on a container are disclosed. The closure includes a base which can be arranged on a container port and can be connected thereto in a fluid-tight manner as well as a closure part connected to the base via a predetermined breaking point. Each of the base and the closure part includes at least one force-enhancing means by which a movement of the base and the closure part relative to each other can be force-assisted in terms of destruction of the predetermined breaking point. The movement of the base and the closure part relative to each other can be a rotary movement of the closure part with respect to the base in the opening direction of the closure part and each force-enhancing means can be a handle in the form of a lever projecting radially from both the base and the closure part with respect to the axis of rotation of the rotary movement.
