Australian swimmer Ryan Napoleon was banned from competition for three months and will miss October 's New Delhi Commonwealth Games, Swimming Australia (SA) announced on Thursday.

SA said it had been informed by the anti-doping agency of FINA, swimming's international governing body, that Napoleon, 20, had tested positive for formoterol, a common asthma medication.

An asthmatic for all his life, Napoleon took medication from an inhaler which was incorrectly labeled, and he subsequently tested positive for a banned substance on the Word Anti-Doping Agency list, SA said in a statement.

The statement said that, in a FINA hearing which was held via teleconference on Wednesday, the panel accepted that Napoleon was not at fault due to a pharmacist's mistake in incorrectly labeling the medication.

The panel said that there was no intent to use the banned substance, permission for which he could have applied, SA said.

FINA did, however, find that as an elite athlete Napoleon had a "reduced responsibility" in this matter and should have been fully aware of the medication he was taking. It therefore applied the three-month suspension.

The decision means that Napoleon will not be able to represent Australia in the 400-meter and 1,500-meter freestyle events in New Delhi of India, for which he had qualified.

"It's devastating," Napoleon said in the statement.

"It's extremely disappointing and something that I have been dealing with since April this year, when I was first notified that there was an issue.

"A mistake was made, and the FINA panel accepted that a mistake was made... but as an athlete I still understand that I have a responsibility to check all my medication thoroughly."

Napoleon won the 1,500m and finished second in the 400m freestyle events at last year's Australian championships.