The body issued a statement on the actions taken by the club and the RFU in the wake of the injury
World Rugby have said that they were "disappointed" with the way in which George North's head injury was handled in a recent game against Leicester.
North landed awkwardly after a mid-air tackle from Adam Thompstone, and footage showed him lying motionless on the ground after the fall. However, he was controversially allowed to return to the field of play shortly afterwards.
A joint Premiership Rugby and Rugby Football Union (RFU) review panel investigated the issue, and while their report stated that North should have been taken off, they stated that they do "not however consider [the] need to impose any sanction against the club or any of its individuals as a result of this incident."
In a statement on Monday, World Rugby reviewed the incident and the handling by both the RFU and Premiership Rugby, and found that: "Despite the failing by the club to correctly apply World Rugby's head-injury management protocols, World Rugby has recognised that the RFU and PRL acted swiftly and appropriately to implement measures with Northampton Saints and other clubs to reduce the probability of future non-compliance."
Noting that "robust head injury protocols defined within the Tournament Player Welfare Standards were not fully adhered to," they "recognise the actions taken by the RFU and PRL as appropriate in order to re-emphasise the protocols and are encouraged by the renewed efforts."
World Rugby also stated it was "disappointed" by the failure to properly identify and appropriately manage the injury in the wake of the incident.
Chairman Bill Beaumont said: "While we acknowledge that errors in the correct application of the process may happen from time to time, we must continue to strive to make our game as safe as possible for players at all levels of the game.
The head injury management process, including the HIA, is successfully protecting players and what this case shows is that all stakeholders must redouble their efforts to ensure they are implemented fully and correctly [...] World Rugby will continue to work closely with all unions to ensure an environment of compliance in this important area.”