LONDON - WBO heavyweight champion Joseph Parker has labelled IBF and WBA champ Anthony Joshua "the king of steroids", but Joshua doesn't seem to mind.

The two will square off in a title unification showdown in Cardiff on March 31, with Joshua, Britain's gold medalist at the 2012 Olympics, looking to add the New Zealander's name to his hit list.

Whoever wins at the 74,500-capacity Principality Stadium will be in line for a bout with World Boxing Council titleholder Deontay Wilder of the US.

After his fight with Joshua was confirmed on Sunday, Parker gave an interview to New Zealand's Radio Sport in which he said: "They call me the king of pies, but I call him the king of steroids."

But Joshua, speaking to reporters at London's Dorchester Hotel on Tuesday, said the "pies" jibe was the work of British television chat show host Graham Norton and dismissed Parker's allegations of drug use.

"I've heard so much boxing trash talk that nothing's new anymore," Joshua said.

"Can I sue him?" he asked to laughter from reporters.

"I know my records are clean," said the 28-year-old Englishman. "That's why I don't bite at it.

"It is what it is. If I'm not clean, you'll find out after this fight. If I haven't been clean for all my other fights, you'll see me struggle against Parker because anything I have been taking will be out of my system.

"You'll find out this fight whether I am a superhuman or if I've got something that pushes the superhuman power he says I have.

"Trash talk has a place in boxing if it's natural, but you shouldn't use it as a tool to sell the fight. I would never put on an act to sell a fight."

Both boxers will be putting their unbeaten professional records as well as their titles on the line. Joshua is 20-0 with 20 KOs, while Parker is 24-0 with 18 stoppages.

Parker's camp suggested Joshua has a weak chin, citing how he was knocked down by Wladimir Klitschko last year before getting off the canvas to be crowned world champion.

'Walk with faith'

But Joshua told a broadcast media conference on Tuesday: "It will take more than a human to stop me getting where I'm destined to be.

"That's why I learned to not walk with sight, I walk with faith in this journey so in terms of you, using it as a PR stunt and the rumors you have heard, they are fake news.

"Three times I've been hurt or stopped. What I have learned from those adversities and storms, it will take more than any human to stop me from this journey."

Joshua's only stoppage loss came as an amateur in 2011, when he was KO'd by Romanian southpaw Mihai Nistor.

"It's an exciting time to be a heavyweight," said Parker, sitting alongside Joshua at the news conference on Tuesday.

"This is going to be the hardest camp and most work as I have a big challenge in front of me in Joshua.

"I've watched him for a long time. I know his strengths, he knows mine. I can't wait to have this fight happen on March 31. I can't wait to put on a great performance. Hopefully I will catch him on the chin and knock him out."

Agence France-presse