A composite barrier film has a base layer of polyester with a barrier layer modified polyvinyl amine (mPVA). The mPVA is polyvinyl alcohol/polyvinyl amine copolymer crosslinked with citric acid and an optional additional crosslinking agent such as epichlorohydrin. The barrier layer can be applied by deposition of a reactive aqueous solution onto the base layer, heating and drying to remove water and crosslink the reactants. Excellent barrier properties of the film are obtained by applying and crosslinking the barrier layer during the transverse stretching steps of a biaxial oriented polymer film continuous fabrication process. Superior barrier properties are achieved with transverse stretching by a factor of about 3-4.