World Rugby has again criticised the handling of George North's head injury last month, but opted not sanctioned his club, Northampton.

It is the second time that the Saints have escaped punishment after a joint Rugby Football Union and Premiership Rugby investigation found that the winger wing should not have returned to the field of play after being knocked out in an aerial collision with Adam Thompstone.

In a statement, World Rugby said: 'While it is impossible to completely remove the risk of error, World Rugby remains disappointed that there was a failure in this case to identify and manage the injury appropriately, in particular considering North's medical history.'

World Rugby added that the RFU and Premiership Rugby 'acted swiftly and appropriately to implement measures with Northampton Saints and other clubs to reduce the probability of future non-compliance.'