World Rugby have announced that they will speak with the Rugby Football Union over their decision not to sanction Northampton Saints for their treatment of a head injury suffered by George North.

North, who has a history of head injuries, appeared to lose consciousness following a dangerous tackle from Adam Thompstone during the 19-11 defeat at the hands of Leicester Tigers earlier this month, but was allowed to continue playing after being assessed by medical staff.

The Saints later stood the winger down and faced no further punishment from the RFU, but World Rugby suggested that the decision was not compliant with their concussion protocols.

"World Rugby's number one priority is player welfare and our primary concern is the welfare of George and all players. It is therefore disappointing that apparent non-compliance with the sport's elite head injury protocols led to George remaining on the field of play when he should have been immediately and permanently removed," read a statement.

"World Rugby's recognise and remove protocols state in no uncertain terms that any player displaying clear or suspected signs of loss of consciousness should be permanently and immediately removed from the field of play. In this case, the Head Injury Assessment should not have been undertaken.

"Unions and tournament organisers can access the Head Injury Assessment process for elite competitions, subject to World Rugby's player welfare tournament standards criteria being met. In this incident, it is clear that there was a failure to comply with these robust and well-established protocols, which continue to successfully protect players around the world.

"Specifically, failure in the identification and management of the injury and due consideration of risk when considering North's history were at fault in this unfortunate case. While recognising that there is always a risk of human error, we will seek further information from the RFU regarding the factors behind the apparent non-compliance with World Rugby protocols and the outcomes reached by the independent review group."

North was left out of Northampton's side for this evening's Premiership clash with Sale at Franklin's Gardens.