SYDNEY (AFP) - Australian Olympic swimmer Grant Hackett Wednesday insisted he was in the shape of his life and stripped off for the cameras to prove it after being angered by jibes about his weight.

The two-time Olympic 1500m champion posed in his swimming trunks to head off speculation about his physical conditioning after an unflattering photograph taken after a 10km qualification race in Seville, Spain.

The picture showed Hackett with a solid belly bulging over the top of his skin-tight swimming costume, prompting Sydney's Daily Telegraph to run the headline: "Has Hackett got the guts to race in Beijing."

"Do I look like I'm really that overweight? I don't think I am," Hackett, sporting a rippling six-pack, told media after a training session in Melbourne.

The 27-year-old, who stands 198 centimetres tall (six foot five inches) and weighs 98 kilograms (15.4 stone) said he was "in the best condition of my career" ahead of the Beijing Olympics.

Hackett said he was hurting enough at his performance in the Seville qualifier -- where he finished 15th and was disqualified for obstructing an opponent -- without the added gossip over his weight.

"I've already got a disappointing result to deal with, rather than having people have a personal attack at you as well," he said.

"But I've just got to laugh it off, I can't look at it any other way because I'm not overweight in any sense of the word."

Hackett could see the funny side though, joking that he had been trying to qualify for reality television weight-loss show "The Biggest Loser."

He said his bulging belly in Spain was because he loaded up on 3.5 kilograms (7.7 pound) of food and liquid before the race to ensure he had the energy to last the distance.

The photograph also caught him breathing out and bending over, with Hackett admitting the look was not enhanced by his figure-hugging costume.

"In those sort of circumstances it is just an absolutely unflattering shot," he said.

Hackett's failure to qualify for the inaugural Olympic 10km event leaves him free to concentrate on his 1500m and 400m races, and he said the public could judge his physique for themselves when they saw him competing in the pool.