London - World Rugby told leading referees to be "especially vigilant" when dealing with players guilty of dangerous tackles that risk opponents' heads during the upcoming November internationals.
The past few years have witnessed increasing concerns regarding the potential impacts of concussion injuries on players, with new forms of in-game head injury assessment introduced to try to prevent players returning to action too quickly when they have suffered a damaging blow in what is, at Test level, an increasingly aggressive contact sport.
World Rugby, the sport's global governing body, said it had instructed match officials to be strict when it came to tackles, charges, strikes or kicks that make contact above the shoulder line and to favour firm sanctions for offenders, up to and including red cards for severe examples.
World Rugby match officials' selection committee chairperson Anthony Buchanan said: "World Rugby's number-one priority is player welfare and the laws of the game clearly state that the necks and heads of players are sacrosanct.
"When it comes to foul play, the game is cleaner now than ever before but referees must constantly be alert to head-high hits.
"By taking this strong approach, we are saying to players that tackling an opponent above the shoulder line will not go unpunished.
"In addition, while striking or kicking an opponent is never acceptable, it is a more serious offence when it involves contact with the head or neck."
He added: "Even ball-carriers must be careful that they fend off tacklers legally and do not strike opponents with forearms or elbows."
World Rugby also said all national coaches involved in the November internationals had already been informed of this "re-focus".