Scotland head coach Gregor Townsend believes the TMO bunker system has "taken the game away from referees" at the World Cup.

And he expressed frustration with the lack of action taken for a similar incident in the loss to South Africa.

"I just don't understand what the TMO bunker and the three officials who are there are looking at," said Townsend.

"I think we're trying to look at ways to not give red cards rather than referee what is a legal tackle and what should be a red card."

With the new bunker review system, if the referee is unable to decide if an incident deserves a red card after two video replays they have the option to show a yellow card.

Television match officials then take a detailed look at the footage, with up to eight minutes to make a decision.

"The TMO bunker has not delivered what I thought it would be, which is only if the referee at the time isn't sure if it's a yellow or red card," Townsend added.

"It's taken the game away from the referees.

"This is our showcase. An opportunity to show what is legal and what is illegal, what we want out of the game.

"That's two tackles now. Both upright and both hit the head of our players. One had no sanction, not even a penalty, the second one just a yellow card. I don't think that's good enough."

Taumoepeau's high challenge on Jamie Ritchie forced the Scotland captain off late in the first half.

Against South Africa, Jesse Kriel's head-on-head challenge Jack Dempsey appeared to go unnoticed early in an 18-3 defeat.

"It's very disappointing that our captain was hit on the head and had to be removed - only a yellow card," added Townsend.

Referee Karl Dickson mentioned a "mitigation in terms of height" when explaining the decision to allow Taumoepeau to return. "Jamie didn't even carry the ball that low," was Townsend view.

On a bruising encounter with seven tries for Scotland, Townsend said: "Tonga are very good side. They have good individuals and they are very physical.

"We talked about the work we did in the first 20 minutes might not necessarily lead to points on the board, but we could take away their belief, take away their fitness.

"The fact we got four tries in the first half was probably ahead of what we expected."

Meanwhile, Stuart McInally has had to withdraw from the Scotland squad with a neck injury just 10 days after receiving a call-up.

The former captain was drafted in when fellow Edinburgh hooker Dave Cherry suffered a concussion slipping on hotel stairs.

The third hooker spot will now be filled by Glasgow Warriors' Johnny Matthews.

Uncapped Matthews, 30, will provide support for George Turner and Ewan Ashman and may well feature if players are rested for next weekend's meeting with Romania in Lille.