Former World Rugby medical advisor Dr Barry O'Driscoll warns that elite level rugby union is ignoring concussion safety protocols.
The ex-Ireland full-back resigned from his post with World Rugby - then called the International Rugby Board - in 2012 over its treatment of concussion and the introduction of the 'five-minute rule' which allows players suffering head injuries to return to play if they pass a mid-match sideline assessment.
Dr O'Driscoll, who is the uncle of Ireland and British and Irish Lions centre great Brian O'Driscoll, told BBC Breakfast News that he was particularly concerned for Wales wing George North, who suffered two heavy blows to the head in Friday's Six Nations loss to England.
World Rugby has questioned whether "all concussion management protocols" were followed by Wales over their treatment of Lions wing North.
Liam Williams replaced North between the 26th and 34th minute of the match in Cardiff after he received an accidental boot to the head from England lock Dave Attwood.
North returned to the pitch and in the second half took another heavy blow after clashing heads with team-mate Richard Hibbard, but finished the game.
But Dr O'Driscoll said: "The five to 10 minute assessment he [North] had is meaningless, it's tokenism.
"The actual regulations at this level say that if you suspect concussion, which you had to, you come off and you stay off."
Wales coach Warren Gatland has backed the Wales medical team's assessment of North.
*Available to UK users only