ROB Howley claimed the "integrity of the game has been brought into disrepute" following a controversial finish to Wales' RBS 6 Nations clash against France in Paris.
Wales were left seething after France replacement prop Uini Atonio went off for an apparent head injury assessment, with starting tighthead Rabah Slimani then returning during a remarkable 20 minutes of second-half stoppage time.
Substitute back-row forward Damien Chouly later scored a try, with Camille Lopez's 100th-minute conversion giving France a dramatic 20-18 victory.
Slimani had earlier been replaced, but the France team doctor insisted that Atonio needed an HIA, therefore allowing Slimani to go back on as France laid siege to Wales' line through a series of scrums.
And Wales also left Stade de France amid suggestions that wing George North was bitten during the frenzied finale.
"Integrity in our game is pretty important," Wales' interim head coach Howley said. "What happened towards the last 10 minutes shouldn't happen again on an international rugby field.
"The process leading up to the change of the French tighthead, the way that process occurred, we love our game too much to have those decisions. It was hugely disappointing.
"The process - him (Slimani) warming up prior to him going back on. One of their coaches outside the technical area had a conversation with the doctor, and within a minute of it, the tighthead was taken off.
"In terms of the HIA and the process, I've spoken to Wayne (match referee Wayne Barnes) to talk about that process. The evidence suggests that it is not in the integrity of our game.
"There is a technical area, and you are not allowed outside that. Ultimately, someone has come outside that and allowed the doctor to go on at a break in play, which is outside the laws of the game.
"You can hear Wayne Barnes ask him (Atonio) if he is okay. He (Atonio) said he had a sore back, but that he was okay. And then the doctor comes on, and he goes off.
"Wayne, in terms of the last 10 minutes, that wasn't Wayne's fault. He has listened to a medic.
"You can imagine the emotional fall-out. I don't know what can be done, because ultimately it is the trust of the information between management and a referee.
"Whoever has come outside the technical area - I don't know who it was - but he has been able to get to someone to get on the field, and they were able to make that switch.
"The integrity of the game has been brought into disrepute."
Asked by a journalist during Wales' post-match press conference if he would call it cheating, Howley added: "I just question the integrity of our game, and the decision that was made.
"If you want to call it that, that's entirely up to you. We love our game, which is why we are involved in it. What we witnessed in the last 10 minutes, I haven't seen that before in the international game.
"I have spoken to Jon Davis of the Six Nations committee, and I've been in to see Wayne several times. We will look through the whole footage."