The 18-year-old Australian avenged his shock Olympic loss to Pieter van den Hoogenband, beating the Dutch sprinter by more than a body length in one min 44.06 secs.

Van den Hoogenband, who set the world records for 100m and 200m at the Olympics in Sydney last September, took silver in 1:45.81. Klete Keller of the United States was third in 1:47.10.

Thorpe held the freestyle records at 200m, 400m and 800m coming into the championships at Fukuoka's Marine Messe pool, and he has bettered all three records in winning golds in Japan.

He bounced back from his 200m Olympic loss by shaving 0.82 off his previous best to set a world record at 1:44.69 during the Australian trials in March.

Thorpe said: "I don't think of it as a victory over anyone, rather it was a victory over myself."

"It was a tough race. Pieter is a great guy, a good friend and being in the pool with him is a great privilege."

Van den Hoogenband said it was a tough race and Thorpe just proved too good.

"I wanted to swim my best, but I couldn't," he said.