To package liquids in thin-walled packages while at the same time conferring good mechanical strength upon these packages, an inert gas such as nitrogen and/or carbon dioxide, in the gaseous state is or are introduced into the liquid by means of an injector (22), the liquid becoming saturated or supersaturated with which gas(es); the product obtained is stored in a reservoir (14) at a constant level above which an overhead of the said gas is created at a raised pressure which is constant by virtue of regulating means (3). On demand, this product is transferred, by tapping means (4), to packages which are partially filled with product the surface of which is surmounted with an overhead of the said gas at a raised pressure after the package has been sealed. Use: packaging of liquids, particularly food liquids.