In an interview on the back of the March 31 fight being confirmed, Parker went in on Joshua predicting he took drugs to gain his exceptional physique.
“They call me the king of pies, but I call him the king of steroids,” Parker told the Radio Sports Breakfast.
“Who knows, if you are that big and that muscly, there’s something wrong.
”I have heard word, I have looked at him and I have seen. He has been very close with Klitschko… he has been a reigning champion for a long time.
“So I don’t know… it may be true maybe not.
”I don’t know how he will respond… he may be angry or upset at what we have been saying.
“It’s part of the game. I am not accusing him of using steroids, but I am saying it is a possibility.’
“There are a lot of ways you can dodge drug testing,” the New Zealander added.
Promoter David Higgins has moved to advise Parker against any further comments after working hard with Joshua’s handler Eddie Hearn to get the Cardiff unification over the line.
“I don’t think Anthony Joshua does steroids,” Higgins told Sport Radio.
“I think he trains very hard to the point of boring. I don’t know why he (Parker) said it. The advice from myself will be to drop it and stick to the things we know.”
It will be interesting to see if Parker heeds Higgins’ words when he squares up to Joshua for the first time since landing the contest at a kick-off announcement tomorrow.