At least one inner vessel is provided within a container for storing and/or dispensing gas under pressure to assist in filling the container with gas. The container comprises an outer vessel defining an interior space and a fluid flow control unit for controlling fluid flow into and out of the container. The inner vessel(s) defines a part of the interior space of container and is intended to hold cryogenic fluid in spaced relationship with respect to the outer vessel. Since the inner vessel is in fluid flow communication with the remaining part of the interior space, when the cryogenic fluid becomes gaseous, the container fills with gas. The inner vessel(s) has a mouth for receiving cryogenic fluid from the fluid flow control unit which is free of the fluid flow control unit.