A flame retardant film comprising a polyester containing film comprising on a side thereof, a flame retardant layer. The flame retardant layer comprises a colloidal metal oxide in an amount of 6 g/m2 of more, an inorganic binder in an amount of 2 g/m2 or more, a first flame retardant being a phosphorous containing compound in an amount of 10 g/m2 or more and a second flame retardant being a mineral compound selected from the group of aluminum hydroxide, aluminum trihydrate, magnesium hydroxide, magnesium calcium carbonate, hydrated magnesium carbonate, aluminum oxide hydroxide, boron compounds, antimony trioxide and combinations thereof, the amount of the second flame retardant is 6 g/m2 or more.