Herbert, Leishman and Matt Jones now have a chance of joining countryman and former winner Cam Smith in playing in the famous major championship this year.
In another signal of a thawing of relations towards LIV golfers, the British Open has joined the US Open in offering a direct pathway for players from the breakaway circuit.
The leading player not already exempt in the top five of LIV's individual standings following its Dallas tournament in late June will be given a spot at the world's oldest major the following month.
Australia's Herbert (fourth in individual standings) and Leishman (sixth) are in the early frame after their finishes at LIV Golf's season-opening tournament in Saudi Arabia last weekend.
Smith, courtesy of his Open triumph at St Andrews in Scotland in 2022, is guaranteed a spot as a former winner while Jones is 47th in LIV standings.
The Royal and Ancient Golf Club announced the change ahead of this year's tournament at Royal Portrush in Northern Ireland.
R&A chief executive Mark Darbon says the decision followed an annual review of the Open's exemptions "to ensure that we offer pathways into the Championship based on results achieved on the leading professional tours".
"We acknowledge that players competing in LIV Golf should also have the opportunity to secure places in the Open through its individual season standings as well as existing pathways," Darbon said.
"We are proud to offer a wide range of opportunities to qualify globally and look forward to seeing which golfers will emerge to take their place at Royal Portrush in July."
The US Open announced last week they would award one spot to the leading player from among the top three at LIV's halfway point this year.
LIV Golf chief executive Scott O'Neil said the R&A's decision was a "true testament to the strength of fields and the R&A's commitment to golf fans around the world".
"LIV will continue our mission to bring the best players to the four corners of the world to grow the game," O'Neil said in a statement ahead of his arrival in Australia for LIV Golf's Adelaide tournament starting Friday.
The Saudi-controlled LIV circuit was already assured of representation at Portrush from July 17-20 with Smith, Louis Oosthuizen, Phil Mickelson and Henrik Stenson all former winners of the Open.
Other major winners who play on the LIV circuit, including Bryson DeChambeau and Brooks Koepka, are also exempt.
Other LIV players can claim places through the Open's qualifying series or world rankings but LIV tournaments don't factor in the global rankings.
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