The present invention relates to container and a closure for mounting on the container, the container of the type comprising a container body having a base and a side wall with a top edge defining a container opening opposite the base. The container further comprises a rim and a locking rib which projects from a free end of the rim, and the closure comprises a top wall and a skirt having a closure flange which projects from a free end of the closure wall for snap engagement under the locking rib when the closure is inserted into the container opening. The present invention ensures that a strong seal is maintained between the closure and the container so that the container can be opened and closed frequently without leakages between the container and the closure.