There is described a packaging machine (1) comprising a conveying device (5) for advancing a web (4) of packaging material along a web advancement path (P) at least to a tube forming station (6) at which the web (4) of packaging material is formed into a tube (3) and for advancing the tube (3) along a tube advancement path (Q), a tube forming and sealing device (10) and configured to form the tube (3) at the tube forming station (6) and to longitudinally seal the tube (3), a tensioning device (32) configured to control the tension of the web (4) of packaging material and/or of the tube (3) and a control unit (13) configured to control operation of packaging machine (1). The tensioning device (32) comprises at least one tensioning assembly (33) having at least a first drive roller (34), a second drive roller (35), a first drive motor connected to the first drive roller (34) and configured to actuate rotation of the first drive roller and a second drive motor (37) connected to the second drive roller (35) and configured to actuate rotation of the second drive roller (35) around the second rotation axis (B). The control unit (13) is configured to control the first drive motor and the second drive motor (37) such that a free loop (38) of the web (4) of packaging material expands and/or advances, in use, between the first drive roller (34) and the second drive roller (35).