Former England scrum-half Matt Dawson has said that he is "frustrated" that Australia's victory over Scotland was decided by a controversial penalty.
Referee Craig Joubert awarded the Wallabies a 79th-minute penalty for a deliberate knock-on by Josh Strauss, although Scottish players claimed that Aussie half-back Nick Phipps was the one to make contact with the ball.
Dawson, who was part of England's 2003 Rugby World Cup winning team, has claimed that either World Rugby or Joubert himself should explain why the decision was made.
He told BBC Sport: "I just get frustrated when games are decided by such decisions. I wish Vern Cotter could come out and say 'I'm angry'.
"I also want some accountability. I want a quote from Craig Joubert or from World Rugby to explain themselves.
"The whole tournament has been incredible. I was hugging Gavin Hastings when Scotland scored a try. If that isn't an incredible moment, I don't know what is. There's no reason why the two semi-finals won't be great."
Australia face Argentina in the last four after the Pumas beat Ireland 43-20 in Cardiff.
