(Reuters) -Six more former rugby players on Thursday joined a class-action lawsuit against World Rugby, England's Rugby Football Union (RFU) and the Welsh Rugby Union (WRU) which alleges a failure to protect them from the risks caused by concussions.
Last week law firm Rylands Law said it was preparing a letter of claim on behalf of players battling head injuries after World Cup-winning England hooker Steve Thompson revealed he has been diagnosed with early onset dementia.
The letter of claim, setting out their intention to sue, has been sent to the sport's governing bodies with a total of nine players involved, including England's Thompson and Michael Lipman and former Wales flanker Alix Popham.
Former Wales Under-20 centre Adam Hughes and ex-England under-21 player Neil Spence were among the six new members behind the lawsuit, while four other England and Wales players chose to remain anonymous.
"The players we represent have only recently obtained a diagnosis of permanent brain damage and are suffering from a variety of consequential sequelae including... early onset dementia, depression, and symptoms and signs of chronic traumatic encephalopathy," the law firm said in a statement.
"There is no other reasonable explanation for such diagnoses other than from concussion and sub-concussive injuries sustained whilst playing rugby union in matches and in training sessions."
Hughes, 30, is the youngest player involved in the groundbreaking legal action.
The governing bodies have been given three months to respond to the letter.
In a joint statement on Thursday, World Rugby, the RFU and the WRU said they take "player safety very seriously.
"World Rugby, the Rugby Football Union and Welsh Rugby Union can confirm they have received a letter of claim from solicitors representing certain players and will now take time to consider its contents," the statement read.
"We have been deeply saddened to hear the brave personal accounts from former players.
"Rugby is a contact sport and while there is an element of risk to playing any sport, rugby takes player welfare extremely seriously and it continues to be our number one priority.
"As a result of scientific knowledge improving, rugby has developed its approach to concussion surveillance, education, management and prevention across the whole game.
"We have implemented coach, referee and player education and best practice protocols across the game and rugby’s approach to head injury assessments and concussion protocols has been recognised and led to many other team sports adopting our guidance."
(Reporting by Hardik Vyas in Bengaluru; Editing by Ken Ferris)