The group of former professional and amateur players are suing World Rugby, the Rugby Football Union (RFU) and the Welsh Rugby Union (WRU) for allegedly breaching their duty of care to players.

Their lawyers say the governing bodies failed to protect them from repetitive concussive blows which caused irreversible neurological impairments, including early onset dementia, chronic traumatic encephalopathy and motor neurone disease.

World Rugby, the RFU and the WRU are fighting the lawsuits and their lawyers said in court filings that the claimants would face severe difficulties in winning their case given the "risks inherent in a contact sport such as rugby union".

Friday's hearing was the first in the landmark case, which echoes a similar lawsuit brought in the United States against the National Football League.

The players' lawyers had applied for information from the governing bodies about safety protocols to protect players and their knowledge of the potential risks of playing rugby.

Their lawyer Susan Rodway said in court filings that the players suspect there has been "an abject failure" to keep records of safety protocols or any medical research to support decisions about "the priority of players' safety".

Rodway added that the governing bodies' lack of disclosure suggested that "the game of rugby union has been a gladiatorial contest with the focus on a purely reactive attitude to issues of health and safety".

But the RFU's lawyer Michael Kent said the claimants had not provided any medical reports to support their lawsuit, arguing disclosure was not necessary at this stage.

Judge Barbara Fontaine ruled World Rugby should provide old versions of its concussion management rules, but that no other disclosure was required.