David Higgins, promoter for WBO heavyweight champion Joseph Parker, was shocked to hear that his boxer called IBF, WBA, IBO world champion Anthony Joshua the "king of steroids."

On Sunday it was officially announced that Joshua and Parker would collide on March 31, at the Principality Stadium in Cardiff, Wales.

On a recent program, Joshua and the host poked fun at Parker's physical shape - calling him the king of pies.

Parker hit right back, calling Joshua the "king of steroids" - a reference to the constant rumors that the British superstar's muscular physique may not be natural.

''They call me the king of pies, but I call him the king of steroids," Parker told the Radio Sport 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."

When Higgins was informed of the statements, he made it clear that he believes Joshua is a clean fighter.

He plans to speak with Parker, advising him to stay away from making those type of statements in the future.

However, Higgins does admit that it's not the first time where someone has made statements that linked Joshua to steroids.

"It wasn't my idea and that just came across my desk. But some people say that," Higgins told Martin Devlin on Radio Sport.

"I don't think Anthony Joshua does steroids. I think he trains very hard to the point of boring. I don't know why [Parker said it]. The advice from myself will be to drop it and stick to the things we know."