Phil Mickelson has been linked to an illegal sports gambling ring after a former bet handicapper admitted to laundering nearly $3million from an unnamed client reported to be the championship golfer.

A report from ESPN's Outside the Lines said that Gregory Silveira, 56, of La Quinta, California, reached an agreement to plead guilty on three counts of money laundering that took place between 2010 and 2013.

Silveira is a former bet handicapper and was working for an offshore gambling organization.

An unnamed 'gambling client' listed in court documents is said to be Mickelson.

Mickelson, 45, a five time PGA Tour Major champion, has not accused of a crime and experts say he is unlikely to face charges because federal laws focus on those running gambling operations rather than the source of the money.

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Phil Mickelson, 45 (pictured), has been linked to an offshore sports betting operation after an intermediary agreed to plead guilty to laundering nearly $3million thought to be from the champion golfer

His longtime lawyer did not give a response to ESPN, and said that his client had another attorney dealing with the matter.

An original draft of a plea deal between the government said that the gambling client was 'P.M'.

The 'gambling client' believed to be Mickelson was said to have transferred two lumps of money, $2.475million and $275,000, into one of Silveira's accounts before the money was moved to various other accounts that the handicapper owned.

Officials from the Internal Revenue Service decline to comment on the case beyond the papers that had been filed, and it is unclear what purpose the money being moved served.

Betting on sports is illegal in the US with the exception of Nevada, and officials used the word 'illegal' to describe the millions of dollars transferred because the sums were involved in sports betting.

ESPN's legal analyst Lester Munson said that the money moving around was an 'awkward and obvious attempt to conceal the flow of resources from Silveira's criminal activity'.

Legal experts do not expect Mickelson (left), who is known to enjoy betting, to be charged in connection with the case. Above, he receives his Masters trophy in 2004

He added that Mickelson could have been charged if investigators found that the golfer was complicit in the concealment, rather than just giving money to Silveira.

Mickelson was previously fined by the PGA Tour for gambling and winning a much smaller amount of money, wagering $25 at 20 to 1 odds that Jim Furyk would sink a shot.

He was also linked to a federal insider trading investigation involving financier Carl Icahn and tycoon Billy Walters.

The accusations centered around well-timed stock trading during Icahn's offer to buyout Clorox in 2011, according to the Wall Street Journal.

Mickelson was cleared in the case.