World No.2 Smith would become easily the highest-ranked signing in a major coup for the Saudi-backed league which is led by countryman Greg Norman.

Golf Channel was the first of multiple outlets to report on Sunday (AEST) that Smith, Leishman, Americans Harold Varner III and Cameron Tringale, Joaquin Niemann of Chile and Anirban Lahiri of India would join LIV Golf at their next event outside Boston from September 2-4.

ESPN said they were expected to play the event, a move which would jeopardise their Presidents Cup availability as the PGA Tour has said any Tour members who participate in a LIV Golf event will be suspended indefinitely.

The Open champion Smith again declined to comment after completing his third round in the PGA Tour's season-ending Tour Championship in Atlanta on Saturday.

A two-under 68 left Smith tied 18th and 11 shots behind the leader, World No.1 Scottie Scheffler, all but out of contention for the $US18 million ($A26 million) FedExCup first prize and PGA Tour player of the year honours despite his wonderful three-win season.

"Golf Channel was the first to report that Smith, Leishman, Harold Varner III, Cameron Tringale, Joaquin Niemann and Anirban Lahiri would join LIV Golf."

Masters champion Scheffler has already won four times in 2022.

That may be some sort of relief for the PGA Tour as it battles to cope with the impact of its enormously well-funded new rival LIV Golf.

However playing a LIV event would mean Smith, Leishman and Niemann would likely not be allowed to play on the International team against the United States in the Presidents Cup in North Carolina in late September as the PGA Tour has suspended defectors.

Smith and Niemann both earned automatic berths on the International team for the event to be held in North Carolina in late September while four-time representative Leishman was a likely wildcard pick for captain Trevor Immelman.

Chile's Mito Pereira, another automatic Presidents Cup pick, was also reportedly expected to make the move to LIV but Sports Illustrated said he was not scheduled to play next week's event.

"Happy and honoured to be part of the International Presidents Cup team," Perreira posted on Instagram on Saturday.

Immelman seemed resigned to losing some stars as his team chases only its second win against the powerhouse U.S. side in the 14th staging of the Presidents Cup.

"I was chosen by our players to lead the International team to the best of my abilities, and I will carry out this honour fully," Immelman said in a statement to GolfChannel.com.

"All I can control is the experience the 12 players who want to be at the Presidents Cup will have. My wife and I along with our support staff have dedicated two years of our lives to making this Presidents Cup an amazing week for our players, caddies and families."