Red and yellow cards will be shown without hesitation for high tackles at the Rugby World Cup, World Rugby's referee boss Alain Rolland has warned.

With player welfare front and centre at this year's World Cup, Rolland issued the caution to teams ahead of the tournament starting on Friday.

Rolland noted new guidelines aimed at reducing concussion had been drawn up and that the number of red and yellow cards shown would be determined by players, rather than officials.

"We've made it very clear as to what the high tackle framework is, how it would operate and how it is there to protect them. Everything we do is to protect the players," he said.

Referee Alain Rolland. Photo / Photosport
Referee Alain Rolland. Photo / Photosport

"I'd be very confident that they (players) are aware of the high-tackle framework, and how it works."

Rolland's comments come after England coach Eddie Jones described the red card shown to All Blacks lock Scott Barrett for a tackle on Wallabies captain Michael Hooper last month as "ridiculous".

Jones said the sending off "lacked common sense" and that a lack of consistency around refereeing threatened to disrupt the World Cup.

Under the new guidelines, referees must confirm contact with the head first and assess level of danger as Rolland explained.

And while confusion has surrounded the role of TMOs in decision making, Rolland said their role remained unchanged in Japan.

"He's looking at serious acts of foul play, where he can assist match officials," Rolland said.

"(Otherwise) around grounding (the ball) around try time, there are other things that can be checked - forward passes, obstructions, offside."