The invention provides a container closure assembly comprising: a container neck (10) having side walls defining an opening at one end thereof and a lip (14) extending around the opening; a cap (12) for said neck, the cap having a base portion(22) and a threaded skirt portion (24); a first screw thread (16) on the neck; a second screw thread (26) on an inner surface of the threaded skirt of the cap; said first and second screw threads being configured to enable a user to secure, remove and resecure the cap into a sealing position on the neck by rotation of the cap on the neck; a sealing plug (52) extending from said base portion of the cap inside and substantially concentric with said threaded skirt portion of the cap, wherein the sealing plug is an olive sealing plug for forming a seal against an inside surface of the container neck when the cap is secured on the container neck; and a sealing skirt (54) extending from said base portion of the cap intermediate said sealing plug and said threaded skirt portion of the cap and substantially concentric with said sealing plug and said threaded skirt portion of the cap, wherein said cap can be displaced towards said neck from said sealing position by application of an axial force without rotation of the cap on the neck and substantially without plastic deformation of the cap.