An endless carrier belt for a conveyor system, which carrier belt is produced flat from a flexible material, includes a flat body of width L, of central longitudinal plane X and of thickness e, whose top face is designed to support a product to be carried. The flat body contains in its thickness a plurality of longitudinal reinforcing members located in only two regions of the width of the flat body, situated at about a quarter of the way across the width, on each side of the central plane. When formed into a tube, the reinforcing members can be positioned on the horizontal diameter of the cross section of the tube, thus limiting the internal stresses on the structure, especially when the structure is following non-straight paths (corners or curves) in a plane perpendicular to the axes of the endmost rollers of the conveyor on which it is used.