Elham Asghari designed a special 'Islamic' bathing suit adding 6kg to her weight so that she would be allowed to attempt the long-distance swim on the Caspian Sea in June.
But the outfit was apparently not modest enough for the country's conservative religious authorities, and her record was not officially recognised.
Plea: Elham Asghari was denied a 20km swimming record because of her 'immodest' outfit
The 32-year-old took nine hours to swim the 20km (12.4 miles), setting out from the town of Nowshahr into the freezing waters of the Caspian.
She did so in defiance of officials who are opposed to women swimming in open waters because of the risk of displaying their body shapes to men.
