(CNN) -- Five-time major champion Phil Mickelson denied involvement in an alleged insider trading fraud Saturday, saying he is fully cooperating with the investigation.
Mickelson, who is playing in the Memorial tournament in Ohio, spoke to gathered reporters after a third round 72 to leave him way off the pace on two-under 214.
"I have done absolutely nothing wrong," said the 43-year-old American. "That's why I'm fully cooperating in every way I can and will continue to do so."
His comments mirrored an earlier statement released Saturday to CNN by his agent.
"I wish I could fully discuss this matter, but under the current circumstances it's just not possible," he added.
The FBI probe is examining stock trades by Mickelson, investor Carl Icahn and a well-known Las Vegas gambler, Billy Walters, law enforcement sources told CNN.
It centers around trades made three years ago after Icahn made an investment in Clorox (CLX, Fortune 500), according to the sources, who are not authorized to speak publicly about the case.
Icahn bought shares in Clorox and later announced a takeover bid for the company, causing shares to rise significantly.
According to reports in the Wall Street Journal and New York Times, the FBI and the Securities and Exchange Commission are investigating whether Icahn tipped off Walters and Mickelson about the investment plans.
Mickelson said FBI agents had approached him after his first round Thursday, but he had decided to continue playing in the final warmup event before the U.S. Open at Pinehurst later this month.
"I think that as a player you have to be able to block out whatever is going on off the golf course and be able to focus on the golf course, and it's not going to change the way I carry myself," he said.
"I'm not going to walk around any other way."
Mickelson is one of the most popular golfers in the world and he was acclaimed after his superb victory last year at the British Open.
Only a victory in the U.S. Open eludes him to complete his set of the four majors, but he has been in indifferent form in 2014 without a top 10 finish on the PGA Tour.
By contrast, Masters champion Bubba Watson is enjoying the best season of his career and led the tournament by a shot going into the final round.
He shot a three-under 69 for 12-under 204 with unheralded Scott Langley his nearest challenger.
Watson is bidding for his third win over the season but will face a likely strong challenge from Hideki Matsuyama of Japan, who was two shots behind with world number one Adam Scott three back.
Overnight leader Paul Casey of England fell back with a 78 to be in a group tied on eight-under which included Jordan Spieth.