The present invention relates to a packaging machine (500) for packaging pourable food products and producing sealed packages, comprising means for longitudinally sealing a web of continuous packaging material to form a tube, and sealing means for clamping and sealing the product-filled tube at spaced intervals. Said sealing means comprises a first two sets of mutually cooperating first heat sealing jaws (10) and first counter sealing jaws (20) respectively, and a second two sets of mutually cooperating second heat sealing jaws (10) and second counter sealing jaws (20) respectively. The sealing jaws (10,20) of at least one of said first and second two sets are carried by chain conveyors which are manageable between a first and a second state to make the packaging machine operable in a first state and in a second state, allowing manufacturing of different types of packages.