Dozens of former amateur rugby players have written to a number of the sport's governing bodies, alleging not enough was done to protect them from brain injuries ahead of a potential lawsuit.
A letter of claim has been sent to World Rugby, the Rugby Football Union, which oversees English rugby, and the Welsh Rugby Union by more than 55 amateurs.
The group includes several retired female internationals, elite male players who took part in the sport before it turned professional in 1995, elite youth-teamers and the family of a male rugby player who died due to chronic traumatic encephalopathy.
Their focus is on securing damages for themselves and their families in addition to trying to make the game safer for future generations.
Law firm Rylands Garth, which is behind the case, already represents more than 275 former professional athletes with brain damage, including England's 2003 Rugby World Cup winner Steve Thompson and former Wales captain Ryan Jones, who have issued similar actions against various governing bodies.
Richard Boardman of Rylands Garth said: "It doesn't matter what level of the game you played or are playing at, whether it's at school or adult rugby, and as a professional or amateur, male or female, we are sadly seeing the same alarming neurological impairments at all levels of the game.
"This is a life-and-death issue for many. The vast majority of the current and former players we represent love the game and don't want to see it harmed in any way.
"We now also represent the estates of deceased players who were found to have CTE post-mortem, which is definitive proof that a contact sport was responsible. Those involved just want to make the sport safer so current and future generations don't end up like them."
Boardman said the claimants were asking rugby's governing bodies to make "immediate changes" including a mandatory limit on contact in training and improving pitchside assessment.
World Rugby chairman Bill Beaumont spoke about the issue of player welfare in an open letter on Wednesday looking forward to 2023, which includes the World Cup in France.
"We set out to make 2022 a year of focus on welfare in rugby and I am proud of what we have achieved together," he said. "But we must not and will not stand still.
"This year will bring independent and peer-reviewed research from our world-leading smart mouthguard studies. This data will provide insight into the game like never before and will form the basis for further advances in welfare-supporting law, protocols and guidelines.
"There will be developments, too, related to the other key pillars of our welfare plan, including our commitment to education and support for former players. All of this will help to secure rugby's place as the most progressive sport on player welfare."