Stunned PGA Tour players said they had been left in the dark about the surprise merger with LIV Golf that shocked the world of golf on Tuesday.

Shortly after the unexpected announcement that golf's bitter battle between the established PGA Tour and the Saudi-backed breakaway LIV Golf was over, players took to social media to react.

And it was clear that PGA Tour players had no idea that a deal was in the offing while LIV players were delighted at the end of the conflict.

"The hell is going on? Very curious how many people knew this deal was happening. About 5-7 people? Player run organization right?," said American player Michael Kim.

Canadian player Mackenzie Hughes was quick to note the sharp about-turn from PGA Tour officials who had been vehemently opposed to the Saudi-backed tour.

"Nothing like finding out through Twitter that we're merging with a tour that we said we'd never do that with," he wrote.

South Korea's An Byeong-hun noted the difficult situation for players who had backed the PGA Tour's stance against LIV.

"I'm guessing the LIV teams were struggling to get sponsors and PGA tour couldn't turn down the money. Win-win for both tours but it's a big lose for who defended the tour for last two years".

US player Dylan Wu echoed An's comments, blasting the "hypocrisy" of PGA Tour commissioner Jay Monahan.

"Tell me why Jay Monahan basically got a promotion to CEO of all golf in the world by going back on everything he said the past 2 years," Wu wrote. "The hypocrisy. Wish golf worked like that. I guess money always wins."

Reaction was much more positive among players on the LIV Tour with one of their most prominent players, six-time major winner Phil Mickelson quickly taking to social media.

"Awesome day today," tweeted Mickelson above a link to a news story on the merger.

Brooks Koepka, who became the first LIV golfer to win a major with his triumph at the PGA Championship last month, took aim at one of LIV's strongest critics, television golf pundit Brandel Chamblee.

"Welfare check on Chamblee," Koepka tweeted.

Former US President Donald Trump, who hosted several LIV events on his courses, gave his endorsement of the deal.

"Great news from LIV Golf. A big, beautiful and glamorous deal for the wonderful world of golf. Congrats to all," he posted on social media.

Ireland's three-time major champion Padraig Harrington — who turned down an offer to join LIV last year — meanwhile expressed surprise at the speed with which the merger had been agreed.

"Surprised that this merger has happened so quickly but not surprised it's happened," Harrington wrote on Twitter.

"Definitely in the financial interest of both sides. Definitely in the financial interest of the players even though some of those who gain will feel like they're losing. Good for the cohesion of global golf."

In Toronto, PGA Tour players preparing for this week's Canadian Open also reacted with surprise.

Canada's Adam Hadwin struck a pragmatic note though when asked whether the merger would present players with moral concerns given criticism of Saudi Arabia's human rights record.

"I've dedicated my entire life to being at golf's highest level," Hadwin said. "I'm not about to stop playing golf because the entity that I play for has joined forces with the Saudi government."