Both the Force and Rebels maintain the ARU has no right to remove their teams in SANZAAR's downsizing to a 15-team tournament, with WA Rugby having commenced legal action and the Melbourne club seeking compensation.

Clarke, who endured criticism from the West Australian franchise in recent weeks around his former links to the Rebels and Brumbies, had been considered a future CEO of the embattled national body.

The former advertising executive returned to the ARU in 2014 as general manager of professional rugby, operations and marketing. His elevation to chief operating officer in 2015 was his second stint in the role, after serving in the same position in 2006-07.

"Rob Clarke is one of the outstanding sports administrators in the country and has given wonderful service to the game through the ARU, the Brumbies and Melbourne Rebels over the course of a decade," Pulver said.

"His resignation was difficult to accept but Rob has decided the time is right to pursue a different course along with his family and he deserves to be incredibly proud of his career in the game. When I look at the values of our game it is hard to imagine someone who embodies those values both in a professional and personal sense more than what Rob does. He is a tremendous loss for the organisation. I am ever-grateful to Rob for his contribution to the ARU and I wish him the very best for his future."