A collapsible container (C) primarily for transporting liquid, powdered or granular material is of polygonal transverse section and includes a plurality of rigid sidewalls (2, 4, 6, 8) interconnected by flexible hinges (16), each sidewall (2, 4, 6, 8) having a top flap (26, 28, 30, 32) and a bottom flap (18, 20, 22, 24) interconnected therewith by flexible hinges (48, 40). At least one, and preferably two, straps (56, 58) are threaded through the upper and lower hinges (48, 40) and through the container to provide external support across the base of the assembled container, and such as not to interfere with the collapsibility of the container, lifting means (60) being provided at the ends of the or each strap (56, 58).