Six Nations chiefs have launched an investigation into France’s controversial replacement switch against Wales.

Tournament officials are to probe the circumstances behind the replacement of Uini Atonio by Rabah Slimani in the closing stages of their victory over Wales last month in a match that lasted 100 minutes.

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.

After the 20-18 defeat in Paris – that condemned Wales to a fifth-place finish – coach Rob Howley questioned the integrity of the French use of their bench and said: “There is evidence to suggest the integrity of the game has been brought into disrepute.”

Now, France’s move has been referred to the tournament’s Untoward Incident Review Group. 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 (£26,000) after he accepted a misconduct charge following allegedly critical post-match comments he made to the media about referee Wayne Barnes.