Carl Icahn, Phil Mickelson 'in insider trading probe'

Phil Mickelson, a three-time Masters champion, is one of America's highest paid sportsmen

The FBI is investigating possible insider trading involving billionaire investor Carl Icahn, golfer Phil Mickelson and Las Vegas gambler William Walters, reports say.

The inquiry is reportedly examining whether Mr Mickelson and Mr Walters may have traded shares illegally, based on information provided by Mr Icahn.

Mr Mickelson's lawyers say he is not the target of an investigation. Mr Icahn denies giving insider information. Mr Walters has not yet commented.

Mr Mickelson, 43, has won five major championships and is one of the US's highest-paid sportsmen

The FBI, along with the Securities and Exchange Commission and federal prosecutors in Manhattan, are said to be looking into trading in two different stocks.

The investigation, which began three years ago, is focusing on trades in cleaning products company Clorox.

Carl Icahn is a vocal critic of some of America's largest corporations

Mr Icahn, a billionaire investor and prominent activist, was mounting a takeover bid for Clorox around the time that Mr Mickelson and Mr Walters placed their trades, the New York Times reports.

"We do not know of any investigation," Mr Icahn, 78, told Reuters news agency, saying he was proud of his 50-year "unblemished record".

Investigators are also reportedly looking into trades that Mr Mickelson, a three-time Masters champion, and Mr Walters made relating to Dean Foods, the Wall Street Journal reports (pay wall).

The New York Times quotes sources saying federal authorities are looking into trades placed in August 2012 just before the company announced quarterly results.

Those trades appeared to have no connection to Mr Icahn, the newspaper added.

The FBI and other federal agencies have not commented publicly on the allegations.

None of the men have been directly accused of any wrongdoing.