The swimming judge who disqualified gold medal winner Aaron Peirsol at the Athens Olympics is standing by his claim that the American backstroker broke the rules.

French judge Denis Cadon said he was correct to report Peirsol for an illegal turn on the last lap of Thursday night's 200 backstroke final.

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Peirsol was disqualified after the judge said he illegally rolled on his stomach and kicked off the wall on one of his turns but later won an appeal allowing him to be reinstated as the gold medallist.

"There was a problem, there was a fault," Cadon, a judge with 25 years experience, said on Friday. "I did my job, I'm here for that."

Swimming's world governing body FINA released a statement saying Peirsol had been reinstated because there was an error in the disqualification form, signed by Cadon, Russian judge Felix Mikhailov and Singaporean referee Woon Sui Kut.

"The DSQ (disqualification) of the swimmer in lane 4, Peirsol Aaron (USA) was not accepted due to the detail of the reason being inadequate."

FINA's Cornel Marculescu said the officials would be reprimanded for their botched paperwork.

"You will not see them again," he said. "They were immensely experienced judges but this is the Olympic Games."

Britain and Austria both protested that the disqualification should still stand but their appeals were rejected.

However, the British, whose swimmer James Goddard would have won a bronze medal if Peirsol had been kicked out, are considering taking their case to the Court of Arbitration for Sport (CAS).

"Any talk of an appeal is premature, it's up the chef de mission to decide that, but we are looking into it," British Olympic Association spokesman Philip Pope said.

"The chef de mission will meet with the head swim coach and our lawyers and they will decide what to do."

CROWD ENCOURAGED

Peirsol led from start to finish to easily win the final five metres ahead of Austrian Markus Rogan and Romania's Razvan Florea. Goddard was fourth.

Peirsol, who also won gold in the 100, was climbing out of the pool when he was told he had been disqualified.

He raised his arms, encouraging the crowd to howl in protest and reports said his mother Wella fainted.

Opinion over whether Peirsol really did break the rules is split, but coaches from the United States and Australia did agree that the rule needed changing.

"We need to change that turnover rule," U.S. head coach Eddie Reese said. "The longer you are on the stomach the slower you're going so you penalise yourself.

"Rules are designed to prevent from gaining an advantage and that has no bearing in it."

Australian head coach Leigh Nugent agreed.

"It's been a contentious rule for a long time," he said. "If you have a momentary lapse in concentration you're gone."