London (AFP) - Rugby Players' Association chief Damian Hopley says training methods need to be addressed "very quickly" after a group of ex-professionals said the sport had left them with brain damage.
England World Cup winner Steve Thompson and seven other players are planning legal action against World Rugby, the Rugby Football Union and the Welsh Rugby Union for negligence.
"It's been very distressing for everyone," Hopley told the BBC.
The former England international called for a series of measures including more education, greater consistency in refereeing and a reduction of contact training.
"A big percentage of injuries occur during training so I think that has to be part of the opportunity to address these things and look at what can we do to make the game safer, as has been talked about," he said.
"Perhaps training protocols is something we need to address very quickly."
Thompson, 42, has been diagnosed with early onset dementia and says he has no recollection of winning the World Cup with England in 2003.
Former Wales international Alix Popham and ex-England player Michael Lipman are in their early 40s and suffering from early onset dementia and probable chronic traumatic encephalopathy (CTE).
Lawyer Richard Boardman, who is representing the players, told the Press Association news agency up to 50 percent of former professionals could end up with neurological complications in retirement.
He said the initial group could increase to 10 or 11 former players in the coming days and that he was working with a group of 110 ex-players overall, ranging in age from their 20s to their 50s.
But Exeter director of rugby Rob Baxter made a robust defence of the sport's concussion measures on Thursday, saying there was "little value" in comparing the issue now with historic cases.
Baxter, whose team are the reigning English and European champions, said rugby was "probably the leader in monitoring return-to-play safety practices around head injuries".
"Whatever's happened with these guys, however unfortunate it is, is a way down the line," he said."The difference between then and now is so significant that there's almost very little value in trying to compare the two.
Baxter said it was "disingenuous" for people not to recognise the steps rugby had taken to make the sport safer.
"As tragic as it can be for the individual involved -- and I fully accept that -- I don't know whether there's even a higher prevalence of early onset dementia in a rugby player than there is the general population," he said.
Baxter's comments follow those of Bristol rugby director Pat Lam, a former team-mate of Thompson's at Northampton, who believes the game is much safer now than it used to be.
"For us as coaches, it's around correct technique and safety of the player right now," he said."There is such an awareness to make sure the player is safe.
"I cringe when people say the game has gone soft and it should go back to the old days."
A World Rugby spokesman said: "While not commenting on speculation, World Rugby has the utmost respect for the well-being of all players, including our former players.
"We are unwavering in our commitment to evidence-based injury prevention strategies, and the priority area of concussion education, management and prevention, and act based on the latest available research, evidence and knowledge."