KAZAN, Russia (AFP) - Katie Ledecky of the United States demolished her own world record as she retained the women's 1,500m freestyle world title in Tuesday's final.

Having broken the world record in Monday morning's heats, the 18-year-old triple world record-holder knocked 2.23sec off her own personal best to clock 15min 25.48sec.

New Zealand's Lauren Boyle took silver at 14.66sec back while Hungary's Boglarka Kapas came home for bronze at 21.61sec adrift.

Other finalists: 4 Lotte Friis (Den) 15:49.00. 5 Jessica Ashwood (Aus) 15:52.17. 6 Sharon van Rouwendaal (Ned) 16:03.74. 7 Kristel Koebrich (Chi) 16:06.55. 8 Aurora Ponsele (Ita) 16:09.57.