Phil Mickelson will not defend his PGA Championship title after withdrawing from the competition, which takes place next week.

Mickelson has not played since February after he decided to take a break from professional golf following the backlash to his controversial comments over the Saudi Arabia-backed Super Golf League – now officially called the LIV Golf Invitational Series. 

The 51-year-old, who became the oldest major winner in history when he triumphed the PGA Championship at Kiawah Island last year, said Saudi Arabia has "a horrible record on human rights", but added he was willing to commit to the league as it was "a once-in-a-lifetime opportunity to reshape how the PGA Tour operates". 

Mickelson apologised for his comments, but his hiatus from the sport saw him miss the Masters for the first time in 28 years.

The six-time major winner was expected to feature at Southern Hills Country Club in Tulsa, after he was included in the final field, yet tournament organisers confirmed on Friday that Mickelson had opted out.

"We have just been informed that Phil Mickelson has withdrawn from the PGA Championship," a statement on the PGA Championship's official Twitter channel read.

"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 Amy the very best and look forward to his return to golf."

Mickelson, along with several other golfers, has requested a release from the PGA Tour to compete in the LIV Golf Invitational Series, which is due to start next month, though it was not confirmed that he would definitely play in the first event in London.

The PGA has, however, declined those release requests.