The federal government may have a tough time bringing an insider trading case against Masters champion golfer Phil Mickelson, activist investor Carl Icahn and sports gambler William Walters. (Reuters)

Phil Mickelson said he has cooperated with a government investigation into possible insider trading and maintains that he has “done absolutely nothing wrong.”

Mickelson found himself making front-page headlines when the Wall Street Journal and New York Times late Friday reported that he, investor Carl Icahn and Las Vegas gambler William T. (Billy) Walters are the subjects of an investigation by the FBI and the Securities and Exchange Commission  into possible illegal trades allegedly made by Mickelson and Walters based on nonpublic information they may have obtained from Icahn about his investments in public companies.

“I have done absolutely nothing wrong. I have cooperated with the government in this investigation and will continue to do so,” Mickelson, who is playing in the Memorial this weekend in Dublin, Ohio, said in a statement issued by his manager Saturday morning. “I wish I could fully discuss this matter, but under the current circumstances it’s just not possible.”

His lawyer, Glenn Cohen, told Reuters that Mickelson is not a target of the probe.

Icahn acknowledged a business relationship with Walters but said that he did not know Mickelson personally. Icahn and Walters denied awareness of any probe. “We do not know of any investigation,” Icahn told the Journal. “We are always very careful to observe all legal requirements in all of our activities.” The idea that he was involved in improper trading, he said, was “inflammatory and speculative.”

The Journal, which first reported the story, said the probe began three years ago, when Icahn acquired a 9.1 percent stake in Clorox. In July 2011, his offer of $10.2 billion caused stock in the company to spike. “Well-timed trading around the time of his bid caught the attention of investigators, who began digging into the suspicious trading in Clorox stock, the people familiar with the probe said,” the Journal’s Susan Pulliam and Michael Rothfeld wrote.

Icahn’s bid was rejected by Clorox and, after an unsuccessful proxy battle for control of the company, he had sold his stake by the end of 2011. Later, according to the Journal, investigators expanded the probe to look at trading patterns by Walters and Mickelson relating to Dean Foods.

Walters, who owns a number of golf courses, and Mickelson play golf together, notably in the Pebble Beach Pro-Am. Walters, reached by the Times, said: “While I don’t have any comment, pal, I’ll talk to you later.”

The Times noted that the “for two years, authorities had little to go on besides trading records and a hunch. Then last year, FBI agents approached Mr. Mickelson at Teterboro Airport in New Jersey, one of the people briefed on the matter said, asking the celebrity golfer to discuss his trading. It is unclear whether Mr. Mickelson knows Mr. Icahn or provided any evidence implicating him or Mr. Walters in the trading. It is possible that the investigations will not produce any charges.”