SCOTTSDALE, Arizona, Jan 30, 2013 (AFP) - In a Sports Illustrated article published Tuesday, the Fijian was linked to a two-man company called Sports with Alternatives to Steroids (SWATS) and its deer antler spray that purportedly helps athletic performance.
The spray contains IGF-1, an anabolic hormone that boosts muscle growth and is banned by all major sports organizations.
Singh, three weeks shy of his 50th birthday, admitted using the spray but said he had no idea it violated PGA anti-doping rules and added that he was cooperating with a PGA Tour investigation into the matter.
"While I have used deer antler spray, at no time was I aware that it may contain a substance that is banned under the PGA Tour Anti-Doping Policy," Singh said in a statement.
"In fact, when I first received the product, I reviewed the list of ingredients and did not see any prohibited substances.
"I am absolutely shocked that deer antler spray may contain a banned substance and am angry that I have put myself in this position.
"I have been in contact with the PGA Tour and am cooperating fully with their review of this matter."
The article said PGA players were warned about the deer antler spray in 2011 after PGA player Mark Calcavecchia was told by the tour to stop endorsing another spray by SWATS.
In the story, Singh said he used the spray "every couple of hours" and used special chips and a beam ray the company claimed would enhance his body.
"I'm looking forward to some change in my body," Singh was quoted as saying in the story. "It's really hard to feel the difference if you're only doing it for a couple of months."
Singh's 34 career PGA triumphs include three major titles, at the 2000 Masters and the 1998 and 2004 PGA Championships.