Rugby union's world governing body has requested "a full report" from Welsh rugby chiefs after George North suffered two blows to the head during Friday night's Six Nations opener against England.

The juggernaut Wales wing took an accidental boot to the head from England lock Dave Attwood in the first-half, and he was temporarily replaced by Liam Williams while he underwent mandatory concussion assessment.

North subsequently returned to the field, but he then clashed heads with team-mate Richard Hibbard during the second half in what appeared to be a worse incident, and that has now attracted World Rugby’s attention.

North did not go off a second time, playing on as England started their Six Nations season with a 21-16 victory.

In a statement, World Rugby, formerly the International Rugby Board, said: “World Rugby has requested a full report from the Welsh Rugby Union (WRU) following an apparent head impact sustained by Wales wing George North in the second-half of Friday night’s RBS 6 Nations match between Wales and England at the Millennium Stadium, Cardiff.

“North, who sustained the impact in the 61st minute of the match, remained on the field. And, having undertaken an initial review of the broadcast footage, World Rugby is seeking to establish from the WRU whether all concussion management protocols were appropriately followed.

“Concussion management and education is at the heart of World Rugby’s player welfare strategy designed to protect players at all levels of the game and promote the very highest standards of education, coaching and medical care.”

For their part, the Wales squad management issued a medical update on Saturday that stated North was “currently symptom free,” although they have also viewed footage of the second incident.

“In relation to George North, he passed head injury protocol tests that were carried out in the medical room, in addition to an on-pitch assessment,” Wales said. “He also showed no signs and symptoms when follow-up tests were carried out immediately after the game.

“While George is currently symptom free, retrospective video review of the second incident identified the mechanism of injury which was previously unsighted on the field of play.

“This review has warranted the medical team to manage the player as concussed, although the player currently has no signs and symptoms. He will now undertake a graduated return to play protocol with multiple follow-up cognitive and physical tests.”

The North episode caused a widespread reaction throughout the rugby community.

Former England captain Lewis Moody said on Twitter: “Why was George North not taken off. Terrible decision by the medics. Out cold .”

And ex-England skipper Will Carling tweeted: “I really don’t think George North should still be on the pitch. He looks very dazed....”

North, meanwhile, missed Wales’s victory over South Africa earlier this season after being treated for concussion during the defeat against world champions New Zealand seven days earlier.

Wales also said on Saturday that prop Samson Lee was concussed during the England clash.

“He will also be undertaking a graduated return to play protocol, consisting of a number of cognitive and physical tests prior to returning to training,” Wales added, in their statement.

“Dan Biggar sustained a laceration to his forehead following an accidental collision with team-mate Gethin Jenkins. He will be managed accordingly in the build-up to the Scotland fixture.

“Leigh Halfpenny sustained a mild neck injury that will be treated by the medical team this week. This injury is unlikely to keep the player out for the following week’s fixture.”

Wales resume their Six Nations campaign against Scotland at Murrayfield in eight days’ time.