After getting annoyed with a recent insult, Joseph Parker has come firing back at Anthony Joshua.

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

Parker will stake the WBO world title he captured in late 2016, while Joshua is going to put up his WBA, IBO, IBF belts. Both of their undefeated records will also be on the line.

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."

Parker (24-0, 18 KOs) later would state that he's accusing Joshua (20-0, 20 KOs) of actually using steroids, but also left the door open for those allegations to be true.

''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," Parker said.

"A couple of months ago, I heard him say: 'Why should I be worried about this little kid from New Zealand?' Well, now he's about to find out and the world is about to find out whether AJ can really take a punch."