The invention is an integrally blow-moulded bag-in-container (2) obtainable by blow-moulding an injection moulded multi-layer preform (1). The bag-in-container (2) includes an inner layer (21) forming the bag and an outer layer (22) forming the container, and a single opening (5), the mouth, fluidly connecting the volume defined by the bag (21) to the atmosphere. The container further includes at least one interface vent (3) fluidly connecting the interface between inner and outer layers to the atmosphere, wherein the bag (21) is anchored to the outer layer (22) at at least one point (7) remote from the single opening (5) and interface vent (3). The invention also relates to a process and a mould for the production of the blow-moulded bag-in-container (2).