Italian Paralympic rower Giacomo Perini was disqualified from the PR1 men's single skulls final and missed out on a bronze medal on Sunday for using "communication equipment."
Perini, 28, who had his right leg amputated due to a form of bone cancer, crossed the line in Paris in third place before Australian Erik Horrie was eventually handed the bronze medal.
Britain's Ben Pritchard took gold and Ukraine's two-time champion Roman Polianskyi claimed silver.
World Rowing said Perini "was found to be using communication equipment during the race."
"As a result, the crew has been excluded from the event and will be ranked last," it added.
The Italian rowing Federation filed an appeal, which was rejected, and said it was was preparing to appeal the decision to the World rowing Executive Board.
Welshman Pritchard, 32, claimed Perini had a telephone in his boat in a race where athletes row with their backs to the finish line.
"He had an open phone on in the boat and you're not allowed communication like that," Pritchard told reporters.
Elsewhere, on the final day on the water in Vaires-sur-Marne, Pritchard's compatriot claimed three other medals.
They secured gold in the PR2 mixed double sculls, silver in the PR3 event of the discipline and the PR3 mixed cox four.
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