Phil Mickelson has expressed his "deepest of sympathy and empathy" for the families of the 9/11 victims amid continued criticism over his decision to join the LIV Golf Invitational Series.

The controversial eight-event Saudi-backed breakaway circuit, which got under way in London last week, has a prize fund of $250million that is bankrolled by Saudi Arabia's Public Investment Fund (PIF).

Mickelson and the other American players taking part in the series have been accused by a group representing victims' families and survivors of "sportswashing" – the practice of using sport to improve a tarnished reputation.

Terry Strada, the chair of the 9/11 Families United, said in a statement: "Whether it was the appeal of millions of dollars of hard cash, or just the opportunity to prosecute your professional grievances with the PGA, you have sold us out.

"This is a betrayal not only of us, but of all your countrymen."

Strada cited Saudi Arabia's prominent role in the terror attack 21 years ago, with Osama bin Laden and 15 of the 19 hijackers being Saudi nationals.

In another uncomfortable news conference on Monday ahead of this week's U.S. Open in Massachusetts, Mickelson was asked directly about Strada's comments.

"I would say to the Strada family, I would say to everyone that has lost loved ones, lost friends on 9/11 that I have deep, deep empathy for them. I can't emphasise that enough," he said.

"I have the deepest of sympathy and empathy for them."

Asked if he intended to respond privately to the letter, Mickelson repeated his earlier answer.

Mickelson and the others to have joined up for the series have also faced criticism from their colleagues, with Rory McIlroy – the winner of last week's Canadian Open – among the more vocal of those to speak out against the LIV Series.

"I certainly respect Rory," Mickelson said. "I thought what a great finish on Sunday and a great accomplishment. What a career he has had. I certainly respect him. I respect his ideas. I respect all the players that choose to stay on the PGA Tour.

"I certainly think extremely highly of many of the players on the PGA Tour and their right to their own decisions.

"I gave as much back to the PGA Tour and the game of golf that I could throughout my 30 years here, and through my accomplishments on the course I've earned a lifetime membership. I intend to keep that and then choose going forward which events to play and not."

Justin Thomas called it "sad" that LIV Golf continues to dominate the headlines in the lead-up to the U.S. Open.

LIV Golf's first event took place this past weekend, with South Africa's Charl Schwartzel pocketing $4.75million as the inaugural winner.

Made possible through Saudi Arabia's Public Investment Fund, the upstart tour has thrown exorbitant sums of money at PGA Tour players to poach them away, including Bryson DeChambeau and Dustin Johnson.

Speaking to the media after opting to not play in Monday's U.S. Open practice round, Thomas said the ubiquitous LIV Golf discussion during one of the great weeks on the golfing calendar was "sad".

"I grew up my entire life wanting to play the PGA Tour," he said. "Wanting to break records, make history, play Presidents Cups, play Ryder Cups.

"The fact that things like that could potentially get hurt because of some of the people that are leaving, and if more go, it's just sad. 

"It's really no other way to say it. It just makes me sad, because like I said, I've grown up my entire life wanting to do that, and I don't want to do anything else.

"The people that have gone, like I said, they have the decision that they're entitled to make. Not necessarily that I agree with it one way or the other, but everything has got a price, I guess."

He later added: "You can't go anywhere without somebody bringing it up.

"It's sad. This is the U.S. Open, and this is an unbelievable venue, a place with so much history, an unbelievable field, so many storylines, and yet that seems to be what all the questions are about.

"That's unfortunate. That's not right to the USGA. That's not right for the U.S. Open. That's not right for us players. But that's, unfortunately, where we're at right now."

Thomas was not done there, going on to discuss why he does not think the money is worth it, but also why it is not fair to make character assessments on the players who decided to make the move.

"There's no amount of money that you could get that [can make you happy doing something] you don't love or enjoy," he said. 

"You're still going to be miserable. You're still not going to enjoy it. Although you might be miserable in a bigger house or a nicer car, that doesn't necessarily mean that your life is going to be any better.

He added: "I'm the first to admit that there's times where people do something, and I bash them – obviously not externally – maybe internally with friends or whatever it is. It's not necessary.

"You can disagree with the decision. You can maybe wish that they did something differently… being in the media as a writer, you have to write about it. I understand that. 

"But for people at home to necessarily say that Dustin Johnson is now a bad person, that's not fair. That's just not right.

"Now, again, I said it last week, I'll say it again, do I wish he wouldn't have done it, and am I a little sad about it? Yeah – but it is what it is."

Phil Mickelson will not resign from the PGA Tour and has confirmed he intends to take part in next week's U.S. Open, despite his LIV Golf Invitational Series involvement.

The 51-year-old will end a four-month self-imposed exile from golf on Thursday when the inaugural LIV Golf event gets underway at Centurion Club on the outskirts of London.

Mickelson was met with widespread condemnation after criticising the PGA Tour earlier this year, for which he apologised and vowed to take a step back from the game.

That saw the six-time major champion miss The Masters and the defence of his US PGA Championship, though he is still registered to play at the upcoming U.S. Open.

And while Mickelson refused to confirm whether he has been serving a PGA Tour ban for his controversial comments, he will not voluntarily quit the American circuit.

"I've been a part of the tour for over 30 years and I've had a lot of incredible memories and experiences, tournaments that I've won and lost," he said on Wednesday.

"I've gained a lot, received a lot and I'm grateful for everything the tour has done for me. I've also worked hard to contribute and build and add value to the tour in my time there.

"I worked hard to get a lifetime exemption. I don't want to give that up. I don't feel I should have to. 

"I don't know what's going to happen. I've earned that and I don't plan on just giving it up.

"I've really enjoyed my time on the PGA Tour. I've had some incredible experiences, great memories and I have a lot of strong opinions that it should and could be a lot better. 

"One mistake I've made is voicing them publicly. I will make an effort to keep those conversations behind closed doors moving forward."

Mickelson then confirmed he will compete in next week's U.S. Open in Massachusetts and added: "I'm looking forward to it."

The United States Golf Association, which runs the major, has already announced it will not stop those competing in the LIV Golf series from playing at The Country Club.

Unlike Mickelson, others taking part in the Saudi-backed breakaway LIV Golf circuit – such as Dustin Johnson and Sergio Garcia – have resigned from the PGA Tour.

"I saw that and I think they're making the decision that's best for them personally," Mickelson said.

"I respect that. As a lifetime member I'm not required to play 15 events. I don't have to play any. I can play one. So I don't see a reason for me to give that up."

Mickelson is reported to have been given a $200million signing-on fee to appear in LIV Golf events, but he refused to be drawn on the specifics during a tense news conference.

"Contract agreements should remain private," he said.

Tiger Woods will not play at the U.S. Open this month but plans to be at St Andrews for The Open in July.

The 15-time major champion withdrew from the US PGA Championship last month after shooting a nine-over 79 in his third round.

Woods was playing in only his second tournament since suffering serious leg injuries in a car crash in February 2021.

The 46-year-old had made a sensational comeback at The Masters in April, defying the odds to make the cut at Augusta before finishing 47th.

Woods stated ahead of the US PGA Championship at Southern Hills that he felt "a lot stronger" than he did after making an unlikely Masters comeback, but struggled on moving day in the second major of the year.

The legendary American on Tuesday confirmed he will not feature in the U.S. Open, which starts at The Country Club in Brookline, Massachusetts on June 16.

However, he is aiming to tee off in the JP McManus Pro-Am at Adare Manor in County Limerick on July 4-5 and play in the last major of the year in Scotland, which gets under way on July 14.

He tweeted: "I previously informed the USGA that I will not be competing in the @usopengolf as my body needs more time to get stronger for major championship golf.

"I do hope and plan to be ready to play in Ireland at @JPProAm and at @TheOpen next month. I'm excited to get back out there soon!"

Woods outlined his plans amid a storm in the golfing world, with his compatriots Dustin Johnson and Phil Mickelson having resigned from the PGA Tour to play in the Saudi-backed LIV Golf Invitational Series.

Greg Norman, the CEO of LIV Golf, this week told the Washington Post that Woods had turned down a "mind-blowingly enormous" offer to play in the controversial breakaway series.

Phil Mickelson has requested a release from the PGA Tour in order to feature in the inaugural LIV Golf opener.

The Saudi Arabia-backed golf league will hold its first event in London between June 9 and 11.

According to Sports Illustrated, 15 of the world's current top 100 players are planning to feature in the event.

Mickelson is taking a break from golf after causing controversy with comments surrounding the breakaway competition when he suggested that although Saudi Arabia has "a horrible record on human rights", the threat of the potential new tournaments could be used to "reshape how the PGA Tour operates". 

On Monday, Mickelson registered himself for two upcoming majors – the PGA Championship, which he won last year, and the U.S. Open, which takes place in June.

However, the 51-year-old has also asked to be released from the PGA Tour at the time of the LVI Golf Invitational, with Monday having been the deadline for those requests.

Mickelson's agent, Steve Loy, released a widely reported statement that read: "Our client Phil Mickelson is officially registered to play in the PGA Championship as well as the U.S. Open.

"We have also filed a request on his behalf for a release to play in the first LIV Golf Invitational in London, June 9-11. This request complies with the deadline of April 25 set forth by the PGA Tour to compete in a conflicting tour event."

However, Loy added that Mickelson is unsure as to whether he will definitely play in any of the events he has registered for.

"Phil currently has no concrete plans on when and where he will play. Any actions taken are in no way a reflection of a final decision made, but rather to keep all options open."

Rory McIlroy believes playing patient golf will be the trick to succeeding once more in a major.

The former world number one is a four-time major winner, but the last of those victories came in 2014 at the PGA Championship.

McIlroy has enjoyed plenty of success since then, winning such as the Tour Championship twice, the Wells Fargo Championship twice, the DP World Tour Championship and the Players Championship.

While a fifth major success has eluded him, the 32-year-old is confident his chance will come again if he remains in the right mindset.

"I haven't won a major in the last seven years but I've basically won everything else," he told BBC Sport.

"I've won the Players Championship, I've won FedEx Cups, I've won Race to Dubai, I've won World Golf Championships, I've won national opens. You know, I've done a lot in the past seven years.

"That hasn't included a major championship but I've played good enough golf in those seven years to win one and I'm staying as patient as I possibly can and, as I say, just giving myself chances.

"I don't think there's anything I should or could do differently. I think the one thing that's held me back, especially in the majors over the last few years, is just getting off to slow starts.

"Opening up at Augusta with a 72 or a 71 and not shooting that 67 or 68 that puts you right in the thick of the tournament from the very start.

"I can't go into the first round of a tournament or on a Wednesday night under pressure to try and shoot a good score. I just have to go out there and let it happen.

"Historically when I've got myself up there early in a tournament I've been able to stay there and capitalise on that start."

McIlroy also believes the depth of quality rivals he faces has made the challenge of winning another major even greater.

"I think I haven't given myself enough chances," said the world number eight.

"I think if I'd have had more chances and realistic chances, just putting yourself in those positions, the more comfortable you are going to feel up there. 

"If you keep knocking on the door, one of those doors is going to open for you.

"I had a chance at Carnoustie in 2018, played the final group with Patrick Reed in 2018 at Augusta, tied for the lead with nine holes to go at the US Open last year at Torrey Pines.

"I've had a few chances and just haven't capitalised. I think players are getting better and better.

"When I last won back in 2014 I'd never heard of [Open champion] Collin Morikawa, I'd never heard of [world number one] Jon Rahm.

"A lot of these guys coming through are playing unbelievably good golf. I don't just have to beat five guys."