This invention relates to a coextruded, transparent, biaxially oriented polyester film comprising a base layer (B) and a heatsealable top layer (A) which is peelable with respect to at least CPET. The heatsealable and peelable top layer (A) consists of a) 70 97% by weight of polyester and b) 3 20% by weight of a polyester-incompatible polymer (=anti-PET polymer) based on the mass of the top layer (A), wherein c) the polyester is composed of 20 95 mol % of units derived from at least one aromatic dicarboxylic acid and 5 80 mol % of units derived from at least one aliphatic dicarboxylic acid, the sum of the dicarboxylic acid-derived molar percentages being 100, and d) the layer thickness of the top layer (A) d.sub.A is from 1.7 to 6.0 .mu.m. The invention further relates to a process for producing the film and to its use.