in a method for forming reclosable packages on a conventional form - fill - and - seal machines , first and second interlocking members are fed toward and longitudinally parallel to the filling tube thereof in an uninterlocked condition . a thermoplastic film is wrapped around the filling tube enclosing the first and second interlocking members , and the lateral edges of the film are bonded together to form a longitudinal seam . at least one of the first and second interlocking members is attached by a heat sealing bar to the inside of the tube so formed from the thermoplastic film . a fold is formed in the tube between the first and second interlocking members to bring the members into a facing relationship , and the members are then interlocked with one another . at intervals , transverse seams are formed to produce individual reclosable packages , which may also be separated from one another . the packages are filled with product during the course of their manufacture . the filling tube may taper inwardly so that the fold can be formed and the interlocking members interlocked as a space of increasing width forms between a forming guide and the inwardly tapering filling tube .