As well as ordering a rematch, Mendoza gave Peterson 10 days from Jan 14 to appeal. Peterson, in turn, has filed an official protest against the WBA’s order.
On Wednesday, the IBF had to cancel its hearing in Newark into the fight after Khan and his handlers, Golden Boy Promotions, withdrew from proceedings after learning Welsh would not be present to give evidence.
“We were unable to reach Mr Welsh after repeated attempts to contact him,” IBF public relations director Jeanette Salazar had told Telegraph Sport earlier this week.
“We have no jurisdiction over Mr Welsh as an official, and therefore could not demand his presence. We could only ask him to appear.”
Welsh’s testimony has assumed even greater significance after Mustafa Ameen, the mystery ‘man in the hat’ - seen in video footage querying Welsh’s decisions - claimed on Wednesday that he had “corrected errors” in the scoring.
Ameen has denied any wrongdoing ringside, in spite of having had no official credentials to be at the supervisor’s table.
Ameen, an affiliate of the IBF but an unpaid official, said: “At the end of the third round, I looked down and I saw Mr Welsh’s score. I believe it could have been nine, nine and nine. There was an error. It might have been 26 or 28 but he was off by a point or two. I said, ‘Michael, nine times three is 27.’
“He said, ‘Oh, my God’ and corrected himself. And he said, ‘I’m not feeling well this evening, thank you very much’.”
Khan won the first round 10-8 on all three judges’ cards, having knocked Peterson down in the first round.
Khan announced on his Twitter page that he would never fight for an IBF title again - before removing the comment on Thursday.
Peterson, meanwhile, insisted that despite reports to the contrary, there are no talks ongoing between the two camps for a re-match.