Reigning PGA Championship winner Phil Mickelson, who hasn't played competitively in more than three months, won't defend his title next week at Southern Hills Country Club in Tulsa, Oklahoma.

The PGA of America announced Friday that Mickelson has withdrawn from the PGA Championship.

"We have just been informed that Phil Mickelson has withdrawn from the PGA Championship," the statement said. "Phil is the defending champion and currently eligible to be a PGA Life Member and we would have welcomed him to participate. We wish Phil and [wife] Amy the very best and look forward to his return to golf."

Last month, Mickelson, a six-time major champion, skipped the Masters, an event he has won three times, for the first time since 1994.

Mickelson became golf's oldest major champion by winning the PGA at Kiawah Island in South Carolina at age 50 last year. He hasn't played on the PGA Tour since missing the cut at the Farmers Insurance Open at Torrey Pines in late January.

Mickelson is taking time away from golf after his controversial comments about the PGA Tour and the Saudi Arabian financiers of a breakaway circuit were published by author Alan Shipnuck, whose unauthorized biography of the golfer popularly known as "Lefty" will be released next week.

Mickelson criticized the PGA Tour for its "greed" and said he was looking past the Saudi Arabian monarchy's alleged human rights violations to gain leverage with the tour.

"They're scary motherf---ers to get involved with," Mickelson told Shipnuck during a conversation in November. "They killed [Washington Post reporter and U.S. resident Jamal] Khashoggi and have a horrible record on human rights. They execute people over there for being gay. Knowing all of this, why would I even consider it? Because this is a once-in-a-lifetime opportunity to reshape how the PGA Tour operates."

Mickelson later apologized for his comments.

Longtime sponsors Amstel Light, KPMG and Workday ended their relationships with him. Callaway, which in 2017 signed Mickelson to a contract through the end of his playing career, paused its relationship with him.

PGA Tour pro Charley Hoffman, who also grew up in San Diego and is one of Mickelson's closest friends, told ESPN on Wednesday that he would be surprised if Mickelson played at Southern Hills.

"I think mentally Phil is probably in a really good space right now, to be honest with you," Hoffman said. "I wouldn't be surprised if he didn't play. I don't know if he wants to deal with [the media]. He's done it his whole life. I think he has enough respect for the game that he will play, but it wouldn't surprise me if he didn't. I don't think he wants to deal with it."

According to ESPN Stats & Information, Mickelson is just the fourth golfer in the last 50 years not to attempt to defend his title at a major the next year. Rory McIlroy was the last one in 2015, when he missed The Open after injuring his ankle while playing soccer shortly before the tournament. Tiger Woods missed the 2008 PGA Championship, after winning it in 2006 and 2007, as he was still recovering from knee surgery. Payne Stewart, the 1999 U.S. Open champion, was killed in a plane accident in October 1999.