Former world number one Dustin Johnson will head the field for the inaugural $25 million LIV Golf Invitational Series event in England next week, the Saudi-backed golf circuit said Wednesday.

The American two-time major champion said in February that he would stay with the US PGA Tour, but in an apparent U-turn Johnson was one of two top-20 ranked players listed in the field on the LIV Golf website for the 54-hole tournament starting on June 9.

Former British Open champion and world number 20 Louis Oosthuizen, former Masters champions Charl Schwartzel and Sergio Garcia, plus former US Open champions Graeme McDowell and Martin Kaymer are also in the field.

Six-time major champion Phil Mickelson's name was absent.

Mickelson, who became golf's oldest major champion when he won last year's PGA at age 50, withdrew from defending his crown last month and hasn't played since his controversial comments about LIV Golf and Saudi Arabia were made public in February.

The tournament at Centurion Club at St Albans, north of London, will have a purse of $25 million, almost double that of any major, with $4 million going to the winner.

There were 42 players listed in the 48-player field, with the field to be completed with players who qualify via an Asian Tour-sanctioned International Series tournament beginning on Thursday in London.

Former world number one Lee Westwood and Ryder Cup stalwart Ian Poulter have also signed up for the event.