Britain's Anthony Joshua dismissed a claim by New Zealand's Joseph Parker he is the "king of steroids" ahead of their world heavyweight title unification bout.

The two boxers will meet in Cardiff on March 31, with Joshua, a London 2012 Olympic gold medallist, looking to add Parker's World Boxing Organisation title to the World Boxing Association, International Boxing Federation and International Boxing Organisation belts he already holds.

Whoever wins at the 74,500-capacity Principality Stadium, best known for staging Wales rugby union internationals, will be eyeing a bout with World Boxing Council heavyweight champion Deontay Wilder.

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 newswire 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 in 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," insisted 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 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."

"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."

The issue of drugs in heavyweight boxing has been thrown into sharp relief by the case of Britain's former world heavyweight champion Tyson Fury.

- 'Life on the line' -

Last month Fury, who has repeatedly taunted Joshua, agreed a compromise with UK Anti-Doping (UKAD) over his positive test for the banned steroid nandrolone that led to him receiving a two-year ban backdated to December 2015. The 29-year-old has not fought since being crowned world champion with his shock victory against Wladimir Klitschko in November 2015,

"In this sport, your life's on the line. Anything to do with that type of stuff you have to be careful," said Joshua. "People's lives are on the line, it's not like a game of golf."

Both Joshua and Parker will be putting their unbeaten professional records as well as their titles on the line.

Parker's camp suggested Joshua has a weak chin, pointing out that 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 news conference at the Dorchester Hotel in London 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 rumours you have heard, they are fake news," he added.

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

Joshua has won all 20 of his professional bouts inside the distance, while Parker is unbeaten in a 24-fight career.

"It's an exciting time to be a heavyweight," said Parker, sitting alongside Joshua in 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 know mine. I know his weaknesses and he thinks he knows my weaknesses.

"I can't wait to have this fight happen on March 31...Hopefully I will catch him on the chin and knock him out."