A flame retardant panel structure comprises at least one external metal layer, one or more tie layers comprising one or more functionalized polymers, and a core layer made of a fabric made of glass fibers. The flame retardant panel structure shows comparable flame retardancy properties while being manufactured at reasonable costs with conventional processes such as for example extrusion or calendering. The flame retardant panel structures can be used in applications where flame retardancy and/or fire protection is needed, such as for example in building and construction applications, automotive or railways applications, medical equipments and luggage.