Italian Paralympics 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.
World Rowing told AFP the Italian team have appealed the decision and a reaction from the international governing body was expected by the end of the day.
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.
"With our disabilities we can’' look around. I can’t look behind me
"I don’t know why you would try something like that in the Paralympic final.
"I've never seen it in a race before so it’s really interesting they’ve tried it in a race today," he added.
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.