Thorpe overbalanced on the blocks

Thorpe was thrown out of his heat when he overbalanced on his blocks and fell into the water.

The 21-year-old, who had been aiming for six gold medals in Athens, lodged an appeal but it was rejected.

Under Australia's rules, swimmers must finish first or second in the trials to qualify for Olympic team selection.

His only hope rested on the second-placed swimmer finishing outside the Olympic qualifying limit of 3:52.00.

But Grant Hackett won in 3:43.35 with Craig Stevens securing the second slot with a time of 3:48.08.

He's not a machine and we saw that at the trials Tracey Menzies, Thorpe's coach

Thorpe claimed he had heard a noise before falling into the water but officials upheld the original decision.

"Our determination is that the referee's decision is correct and as a determination of the fact the protest is dismissed so Ian's disqualification stands," said an Australian Swimming official.

The one-start rule was brought in by world swimming governing body Fina in 1998.

Thorpe holds nine of the 10 fastest ever times in the 400m freestyle, including the world record time of three minutes 40.08 seconds set as he won the Commonwealth gold in Manchester in 2002.

Thorpe and his team lodged two appeals to Australian Swimming officials but both were unsuccessful.

"He's never false-started in his life but a rule's a rule," said his coach Tracey Menzies.

"He's only human. He's not a machine and we saw that yesterday.

"A testament of a true champion is putting it behind you."