France's controversial replacement of Uini Atonio by Rabah Slimani in the closing stages of their 20-18 RBS 6 Nations win over Wales has been referred to the tournament's Untoward Incident Review Group.
Slimani had already been substituted but the superior scrummager was allowed to return to the field when France's team doctor sent Atonio for a head injury assessment in the 81st minute.
A converted try after 20 minutes of added time handed the hosts a dramatic victory in Paris, but the re-emergence of Slimani left Wales interim head coach Rob Howley to declare: "There is evidence to suggest the integrity of the game has been brought into disrepute."
Tournament organisers have now finished their initial assessment of the incident and have decided a further review is needed.
A Six Nations statement said: "Following its preliminary investigation into the replacements made in the latter stages of the France v Wales match on 18 March 2017 (and in particular the replacement of Uini Atonio by Rabah Slimani), Six Nations Rugby has decided to refer the matter to the independent Six Nations Untoward Incident Review Group (UIRG) for review.
"Six Nations Rugby will send the file to the UIRG later this week and it is anticipated that the review process will begin shortly thereafter."
In a chaotic finish, Wales wing George North claimed he was bitten by an opponent - although citing commissioner John Montgomery decided video footage was inconclusive and no further action was taken.
France forward Yoann Maestri was also fined €30,000 euros after he accepted a misconduct charge following allegedly critical post-match comments he made to the media about referee Wayne Barnes.