Lawyers for former rugby players will send a letter of claim to World Rugby, the Rugby Football Union and the Welsh Rugby Union on Tuesday in a class-action suit which alleges that their failure to protect them has led to early onset of dementia.
The claim amounts to millions of pounds in damages.
World Cup-winning England hooker Steve Thompson said last week he had no memory of the 2003 final against Australia. Along with other former players, he is looking to hold authorities accountable over concussion protocols.
Thompson, who made 73 appearances for England from 2002-2011, revealed he was suffering from an early onset of dementia in an interview with The Guardian last Tuesday.
"It's the rugby that's put me through this," the 42-year-old said. "I finished up with nothing really at the end of it.
World Rugby deputy chairman Bernard Laporte defended the governing body on Monday.
"We don't know the contents (of the case). World Rugby has been doing a lot in terms of player welfare and safety," he told reporters at the 2023 World Cup draw in Paris.
"I was impressed with the work done on the health and safety of players when I joined World Rugby four years ago.
"We are a model in terms of research, innovation and mastering this area."
The list of potential claims has grown significantly over the past few days and now stands at more than 100 players, according to the Daily Telegraph.
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