The USA's Katie Ledecky has won her third world gold medal at the World Championships in the 200m freestyle final in Kazan.

The 18-year-old was able to beat off a number of sprinters to touch the wall in 1:55.16, with her compatriot Missy Franklin earning a bronze medal.

It was a tight line in the first 50m, with Hungary's Katinka Hosszu just edging ahead, but Franklin stayed in contention by moving second at the midway point.

Franklin and Italy's Federica Pellegrini showed their strength by storming down the final 50m, but Ledecky was able to soar ahead to take the gold.

Pellegrini swam 1:55.32 to claim a silver medal.