Packaging unit and method for producing sealed packages

A packaging unit for producing sealed packages from a tube of a sheet packaging material fed along a feed path having a first axis; unit comprises: jaws movable cyclically along path between a seal position in which they grip and seal tube to form sealing bands of packages, and a rest position in which they are detached from tube; and folding flaps fitted movably to jaws; folding flaps are movable between: an open position in which they are detached from tube, and a fully closed position in which they cooperate with tube for forming folded flaps in package; the jaws are also cyclically movable in an intermediate position, which is arranged between rest position and seal position; folding flaps are movable relative to the jaws into a partly closed position, which is arranged between open position and fully closed position, when the jaws are set in intermediate position.