The United States Justice Department is investigating the PGA Tour for possible anti-competitive behaviour in its dispute with the LIV Golf series.

The PGA Tour has suspended all members who have competed on the LIV Golf tour.

Major winners Phil Mickelson and Dustin Johnson are among the high-profile players to sign up for the new series.

“This was not unexpected. We went through this in 1994 [when a previous rival tour was being mooted] and we are confident in a similar outcome,” read a PGA Tour statement, referring to an investigation by the Federal Trade Commission 28 years ago, which was eventually dropped.

The LIV Golf series has created division within the game and attracted some of the world’s best players, with £200m in prize money up for grabs across its eight announced events, two of which have already been played.

It is fronted by former world number one Greg Norman, chief executive of LIV Golf Investments, of which Saudi Arabia’s Public Investment Fund (PIF) is the majority shareholder.

Many people have criticised the circuit because of Saudi Arabia’s human rights record, although the PGA Tour’s suspension of their members is for breach of contract.

The European-based DP World Tour followed the PGA Tour’s lead in suspending any of its members who played in last month’s opening LIV tournament.

That move prompted 16 players to threaten legal action if the bans were upheld.

England’s Ian Poulter was able to compete at last week’s Scottish Open after his ban was lifted pending a full appeal.

The R&A said last month that LIV players who qualified would be allowed to compete at the 150th Open Championship at St Andrews, which starts on Thursday.