A closure assembly for a container includes a closure cap having an open ended body with a peripheral wall and a top wall provided with a dispensing passage which is defined by a collar arranged to the top wall. A self closing valve is arranged in the closure cap. The valve includes a slit central portion and a skirt extending downwardly from the central portion, which has an outwardly extending flange. The skirt is arranged in the collar and the flange is located below the collar and extends radially outwardly beyond it. On a lower surface of the top wall, a plurality of lips is formed outward from the collar. The lips are folded over the flange such that the latter is partly enveloped between the lips and the top wall so as to secure the valve in the closure cap.