Apparatus for producing a closing system for containers comprising an anti-tampering strip and a re-closable closing body, said apparatus comprising: - a forming station configured to form barrier elements starting from a sheet, wherein the barrier elements are laminar, with a shape and sizes correlated to those of said closing body; - a transport system comprising at least one gripping unit configured to hold said closing system and to move along a feed path, which extends between an inlet station (S') and an outlet station (S"); - a welding and deformation station disposed along said feed path between the inlet station (S') and the outlet station (S"); - a manipulation member configured to pick up said barrier element in said forming station and take it in said welding and deformation station and subsequently attach said barrier element to the closing body; - a deformation member configured so that it can be driven between an inactive position, distant from the closing system, and a work position in which it presses into contact onto a flexible annular portion of said anti-tampering strip in order to fold it back inside said closing system wherein said deformation member is shaped as an annular deformation element disposed around said manipulation member, wherein said deformation member and said manipulation member develop coaxially with respect to each other around a common longitudinal axis, and are mobile with respect to each other in a direction parallel to said longitudinal axis; and - a control unit connected to said manipulation member and to said deformation member and programmed to command at least the functioning of said manipulation member and of said deformation member in a coordinated manner, so that they respectively attach said barrier element onto said closing body and exert a pressure on said flexible annular portion in said welding and deformation station while said gripping unit is stationary in a same predetermined position holding said closing system. - a forming station configured to form barrier elements starting from a sheet, wherein the barrier elements are laminar, with a shape and sizes correlated to those of said closing body; - a transport system comprising at least one gripping unit configured to hold said closing system and to move along a feed path, which extends between an inlet station (S') and an outlet station (S"); - a welding and deformation station disposed along said feed path between the inlet station (S') and the outlet station (S"); - a manipulation member configured to pick up said barrier element in said forming station and take it in said welding and deformation station and subsequently attach said barrier element to the closing body; - a deformation member configured so that it can be driven between an inactive position, distant from the closing system, and a work position in which it presses into contact onto a flexible annular portion of said anti-tampering strip in order to fold it back inside said closing system wherein said deformation member is shaped as an annular deformation element disposed around said manipulation member, wherein said deformation member and said manipulation member develop coaxially with respect to each other around a common longitudinal axis, and are mobile with respect to each other in a direction parallel to said longitudinal axis; and - a control unit connected to said manipulation member and to said deformation member and programmed to command at least the functioning of said manipulation member and of said deformation member in a coordinated manner, so that they respectively attach said barrier element onto said closing body and exert a pressure on said flexible annular portion in said welding and deformation station while said gripping unit is stationary in a same predetermined position holding said closing system.