England captain Owen Farrell's involvement in the upcoming World Cup was thrown into fresh doubt Thursday when World Rugby announced it would be appealing against the decision to overturn his red card in a warm-up match against Wales.

Farrell was sent off at Twickenham last weekend after the 'bunker' review system upgraded an initial yellow card to red after he made contact with a shoulder-led tackle to the head of Taine Basham.

Farrell, who has been banned for previous incidents of dangerous tackling, was facing a six-week ban that could have ruled him out of the start of next month's World Cup in France.

But an all-Australian disciplinary panel caused uproar on Tuesday by concluding that the Foul Play Review Officer "was wrong, on the balance of probabilities, to upgrade the yellow card issued to the player to a red card."

As a result, it ruled fly-half Farrell was free to play again immediately.

However, World Rugby said in a statement Thursday: "Having considered the full written decision, World Rugby considers an appeal to be warranted."

But World Rugby has yet to release the specific grounds for the appeal.

Its statement said: "World Rugby fully supports the important role that an independent disciplinary process plays in upholding the integrity and values of the sport, particularly regarding foul play involving head contact. 

"Player welfare is the sport's number one priority, and the Head Contact Process is central to that mission at the elite level of the sport.

"Having considered the full written decision, World Rugby considers an appeal to be warranted."

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