Video: World Rugby tell Wales that George North should have been subbed following concussion
World Rugby has said Wales winger George North should not have remained on the field after a clash of heads with team-mate Richard Hibbard but it accepts the Welsh Rugby Union's explanation surrounding the incident.
North appeared to suffer a momentary loss of consciousness after the 61st-minute collision with Hibbard in the RBS 6 Nations opener against England four days ago.
The WRU's national medical manager Prav Mathema said on Monday night that had the second incident been seen by medics, then North would have been immediately taken off and replaced.
North came off the field in the first half after receiving an accidental boot to the head from England lock Dave Attwood but was able to continue after treatment.
Here are the incidents:
World Rugby, meanwhile, has also announced that it will be "immediately investigating, evaluating and promoting the implementation" of new measures.
These are the practicality of television match official technology being expanded to identify head injuries as they happen on the field, all elite competitions being requested to provide pitchside video for medical staff, and all elite tournaments encouraged to adopt the Rugby World Cup 2015 player welfare standards.
In a statement, World Rugby said: "Following a full post-incident review, World Rugby believes that Wales player George North should not have remained on the field of play following a head impact in the 61st minute of the Wales versus England RBS 6 Nations match at the Millennium Stadium on Friday night.
"The World Rugby head injury protocol clearly states that a player should be immediately and permanently removed from the field of play where there are any visible symptoms or suspicion of a potential concussion.
"However, following thorough discussions and input from the expert independent Concussion Advisory Group, World Rugby accepts the WRU's explanation that neither the team medical staff nor the independent doctor had sight of the incident, and understands that the medics acted within the framework of information they had at the time and would have taken a different course of action had they had direct pitchside visibility or access to the same broadcast footage seen by those watching on television.
"The impact was the second sustained by the player in the match, following a first half temporary removal for a head injury assessment.
"Having reviewed the incident report, World Rugby can confirm that the WRU followed correct protocols when assessing North following this first incident.
"The WRU has outlined that the player continues to undergo close medical supervision and is undertaking supervised graduated return to play protocols.
"Player welfare is World Rugby's number-one priority, and the incident highlights the importance of ensuring that medical staff are given the best-possible level of support to minimise the chance of a repeat incident and further enhance the protection and support of players."
World Rugby added that independent medics and video review are an important feature of the the 2015 World Cup player welfare standards, which will operate at all 48 tournament games in England and Wales next September and October.
"This approach also includes defined team and event medical staff minimum standards, mandatory completion of World Rugby concussion education, compulsory pre-tournament concussion baseline testing, and a raft of other education modules aimed at further strengthening player welfare," World Rugby added.
"It is World Rugby's intention that these standards are implemented universally.
"World Rugby would like to thank the WRU for its full co-operation, and welcomes the proposed initiatives by the union to strengthen further the ability to correctly identify head impacts on the field of play."