A legal action on behalf of a group of rugby league players suffering from or showing signs of dementia is being worked on, the PA news agency understands.
The players are understood to be in touch with Rylands Law, which has already launched an action on behalf of nine former rugby union professionals diagnosed with brain injuries including ex-England and Wales internationals Steve Thompson and Alix Popham.
No timeline has been put on the rugby league action being formally launched, but the same firm are also understood to be working with the families of former professional footballers who are suffering with dementia.
In each case, the claims will centre on how the sports manage concussion and other sub-concussive impacts. In the case of football, repetitive heading of the ball is being cited as a cause of brain injury.
Another litigation on behalf of former athletes from a range of sports, led by Nick De Marco of Blackstone Chambers and personal injury specialists John Foy and James Byrne of 9 Gough Chambers, is in its early stages.
Leeds director of rugby Kevin Sinfield says it is important that those running his sport do not make assumptions on the issue.
"We need to do a lot more research on it," he said. "As a club at the Rhinos we've invested into some mouthguard technology to do with concussion. I think it's really important that the whole area is researched properly and we get some answers rather than guess and try and make assumptions.
"It's really sad to see Steve Thompson, it's really sad to see Alix Popham, they both played up at Leeds Tykes, when they were our sister club, so I have spent some time with both of them in the past, and it's really tragic the story and the journey that both those players are on."
Asked if it was something which preoccupied his current players, Sinfield said: "I don't think so. It certainly wasn't in my mind as a player. You understand some of the risks to your body when you play.
"We need to do some research on it, we need to actually get the answers and make sure it's thorough so we can make the necessary adjustments, if any are needed."
Five members of the England football team which won the 1966 World Cup have either died with dementia, or are living with it.
Midfielder Nobby Stiles, who died in October, was one of those players. His family donated his brain for research to Dr Willie Stewart at the University of Glasgow.
The family were told that repeated heading had caused severe damage to Stiles' brain, and that he had been suffering from a condition called chronic traumatic encephalopathy (CTE).
"With Nobby, the CTE was widespread throughout and at a high stage," Dr Stewart told the Daily Mail.
"He presented a story which was entirely typical of someone with CTE. All of the pathologies you would expect to see were there."
Figures published by the Rugby Football Union on Monday show the severity of concussion in the sport is at an all-time high.
If sport continues on course of no meaningful change, please unlock this tweet in 2050 when #dementia #cte reports are being discussed pic.twitter.com/sD4kge4Dpp — Dr Willie Stewart (@WillStewNeuro) December 22, 2020
Data covering the 2018-19 season shows players were sidelined for an average of 22 days after suffering concussion during a match. That figure is higher than at any point since statistics were first recorded in 2002, 10 days longer than the mean absence of 12 days per concussion.
Dr Stewart, who tweeted about those figures on Tuesday morning, also wrote on the social media site: "If sport continues on course of no meaningful change, please unlock this tweet in 2050 when #dementia #cte reports are being discussed."
The text was followed by a GIF containing the words: "I told you so."
Stewart described football's announcement of its plans to trial new concussion protocols from next month as being akin to putting "lipstick on a pig".
Football competitions, including the Premier League, are set to trial the use of additional concussion substitutes, but there is no extension to the period for assessing players suspected of a concussion, something Stewart and world players' union FIFPRO has previously called for.
