Australia prop Scott Sio says there's no chance of the Wallabies and New Zealand ever collaborating for an opposed scrum session the way England and Wales have.

The idea was put forward by England coach Eddie Jones to his Welsh counterpart Warren Gatland ahead of their teams' encounters with Argentina and Australia respectively on Saturday.

England forwards coach Steve Borthwick brokered an unprecedented arrangement between the two nations for a 40-minute practice session in Bristol, a city located approximately halfway between the rivals' training bases.

With Welsh referee Nigel Owens watching, the respective forward packs completed 12 scrums and 16 lineouts.

England prop Harry Williams had jokingly teed it up as the "Battle of Bristol." It didn't turn out like that.

"There was a little bit of an edge," England scrum coach Neal Hatley said, "but there was nothing serious. Both sides took a lot from it."

Sio admitted he'd be intrigued by the prospect of a similar hook-up with the All Blacks but couldn't envisage Wallabies coach Michael Cheika ever picking up the phone to Steve Hansen or any other international coach.

"We'd learn a lot but I don't think 'Cheik' would allow it even if we weren't playing them that weekend," Sio said.

"They (Wales) have had a really strong system here for a while now and it's just them trying something new to see if it can improve their game.

"They are a very set piece-focused team and we know we're in for a battle."

- Additional reporting AP