Writing on change.org, amateur player Ed Bartlett said the move would make the sport "a farcical spectacle to watch", with yellow and red cards being "handed out like confetti" and a rise in "head on knee contact", which, he speculated, may "cause more injury?".

Ball carriers will be "encouraged to follow the principle of evasion" and to "avoid late dipping", the Rugby Football Union (RFU) said in a statement on Thursday, but the governing body has stopped short of banning two-man tackles.

Referees, it added, will be asked "to focus on the actions of the ball carrier as well as the tackler when head contact occurs".

The community game in England, meaning clubs, schools, colleges and universities at both age-grade and adult levels, including the National One division and below in the men's game and Championship One and below in the women's game, are affected by the move.

The change is "designed to improve player safety", "reduce head impact exposure and concussion risk in the tackle for both the ball carrier and tackler," the RFU said.

RFU President Nigel Gillingham said: "Players' welfare must always be at the centre of decisions we make about how we play the game of rugby.

"Evidence from our own research and from around the world clearly shows that lowering the tackle height will reduce head impact exposure and the risk of concussion.

The RFU Council, he added, "unanimously supported the decision", predicting that tacklers will use safe techniques "taught from an early age".

Former England player Brian Moore told The Daily Telegraph head injuries had fallen in France after tackling above the waist in amateur games was banned there.

But he also warned of the possibility of "head collisions of two tacklers both tackling lower, and with heads contacting knees" under the new rules.

Ex-Wales international Lee Jarvis posted a picture on Twitter from a match showing players of differing heights, suggesting that the taller player would no longer be able to tackle the shorter one.

Mark Ring, another former Wales international, lamented the decline in tackling standards generally.

Rugby writer Sam Peters, a vocal concussion-reduction advocate, pointed to the timing of the announcement, writing on Twitter that it came after a group of amateur players sued the RFU over the head injuries they suffered during their careers.

Nick Easter, the former England back-rower now coaching at Chinnor in National One, told The Times that a sport "struggling for numbers" was "going to rip away a lot of types of players from the game".

But World Rugby chief executive Alan Glipin welcomed the RFU's "proactive steps". He promised the sport "will never stand still when it comes to player welfare".