Australian Olympic swimmer, Ariarne Titmus, has today broken the 400m freestyle swim world record.

Her time of 3:56.40 beat Katie Ledecky's old record by 0.06 seconds.

"I'm just really happy," Titmus said after the race.

Ledecky's record of 3:56.46 has been held for nearly six years after Ledecky swam at the 2016 Olympics in Rio de Janeiro.

However, Titmus modestly stated she still believes Ledecky is the greatest female swimmer of all time.

"I can't put myself up next to her. What she has done for female swimming has been insane: She's been at this level for 10 years," Titmus said.

Titmus stated that she was not going for the world record, and had entered the race just hoping to do her best, but knew the record was in her reach.