Pallister had already claimed 400m and 800m freestyle gold at the Duna Arena in Hungary's capital city, and set a championship record on her way to glory.

She finished more than 15 seconds clear of her closest rival to take victory in 15min 58.86sec.

Giulia Salin took silver for Italy in 16:14.00, with Chase Travis of the United States claiming bronze in 16:18.04.

Apostolos Papastamos of Greece set a junior world record in the men's 400m medley final.

Papastamos bettered the 4:13.39 set by United States star Carson Foster earlier this month, in a time of 4:11.93.

Ilia Borodin of Russia earned silver in 4:12.95, as Leon Marchand of France completed the podium in 4:16.37.

Pallister's compatriot Bronte Job won gold in the women's 50m backstroke in a blanket finish at the Duna Arena.

Job surged to glory in 27.87, as a dead heat saw Jade Hannah of Canada and Russian Daria Vaskina claim a silver medal each in 27.91.

No bronze was awarded.

Italian Thomas Ceccon pipped Andrei Minakov of Russia to the 50m butterfly title by just 0.02.

Ceccon stopped the clock at 23.37 for gold, with Minakov touching the wall in 23.39.

The bronze medal went to Bulgarian Josef Miladinov in 23.48.