Australian Rugby Union chief Cameron Clyne rejected claims Wednesday that the decision to axe Western Force from Super Rugby had been made in February and dragging out the process had been "a charade".

Mining magnate Andrew Forrest, a heavyweight backer of the club's parent body RugbyWA, said he had come into possession of legal advice sent to the ARU board in February stating the Force was the best team to cut because the legal risk was low.

He added that the document indicated the ARU made the decision to dump the team, rather than Melbourne Rebels or ACT Brumbies, back then and the governing body saying it was considering all options up until this month was "a charade".

"It shows clearly that in late February this year, the advice was received and taken to cut the Western Force for no other reason apart from legal advice," said Forrest, who had reportedly offered Aus$50 million (US$39 million) to support Australian rugby if the Force were saved.

"The Western Force was set up to be ambushed. It was going to be bullied into submission. I call on Cameron Clyne to resign."

The document, supplied by Forrest to the media, suggested axing either the Brumbies or Rebels without cause would constitute an unlawful termination and the risks were high.

But for the ARU-owned Force, it said there was "no legal obligation" to retain the franchise, with the legal risk low.

Australia had to cut one of its five Super Rugby teams as the sprawling trans-continental competition slims down from 18 sides to 15 next year.

The ARU announced the Force's removal in early August, saying it could not sustain five Super teams financially. The club last week won a right to appeal.

Clyne denied the process had been a "charade" and said a decision was only made on August 11.

"For the record, RugbyWA has been provided several opportunities to put its best business case for the Western Force to the ARU board, from April 10 right up until our final request for this information on August 2, 2017," he said in a statement. 

"Andrew, in his press conference this morning, referred to a document or documents which indicated that a decision had been made to remove the Western Force in February.

"This was not the case and there are no documents which contain this information."

Clyne said the legal risk was only one element taken into consideration.

Western Force joined Super Rugby in 2006, but have never made the competition's finals series.