Tyson Fury believes boxing has a big drugs problem and says sport should address the issue of substance misuse by legalising them.

Fury, who challenges Wladimir Klitschko for the WBA, WBO and IBF heavyweight world titles in Düsseldorf on Saturday, has already provoked controversy in the build-up to the fight with his bizarre behaviour at press conferences and expressing unorthodox opinions on a wide range of subjects during interviews.

Now Fury has responded to the former world featherweight champion Barry McGuigan’s assertion that anyone caught taking drugs should be banned from boxing for life.

“I wouldn’t totally agree with that because we live in a democratic world. We have to be open for the future, don’t we?” Fury said in an interview on BBC Radio 5 live.

“I’ve just been told recently that capping things and keeping things in a box isn’t the way to go forward.

“The old-fashioned ways ain’t the ways so I’m all open for drugs because, if we want to go forward in life and be in a democratic world, as they say, then I think being in a democratic world means that we have to be open to different things. Does it or does it not?”

Fury said his natural “jelly” body proved that he did not take substances, but he added that he had no problem if the sporting authorities allowed a free-for-all when it came to drugs.

“Why don’t they just make drugs totally legal in sports, then everybody would be taking drugs, then it would be fully fair then, wouldn’t it?” Fury asked.

“It’s none of my concern really but, if the governing bodies want to do that, then I think it would be a bit fairer because you’ve got all them people taking drugs and when you face a man who is not taking drugs it becomes unfair, doesn’t it?

“It’s a disadvantage. So this is why it’s a big scene, but if everyone was taking drugs then it would be fairer I think because you can’t tell me that 99% of these sports people ain’t taking drugs when they’ve got bodies like Greek gods.

“I know because I’ve trained all my life, I’m fighting for the heavyweight championship of the world. But my body is like jelly. It’s a natural body you see.”

The British boxers Kid Galahad, Enzo Maccarinelli and Dillian Whyte have failed drug tests in recent years while American and continental European boxing has also had several high-profile doping cases.

“I would say boxing’s got a big problem with drugs,” Fury said. “It doesn’t bother me because at the end of the day it’s determination over drugs any time. If a man wants to pump himself full of drugs, it’s only shortening his life, isn’t it?

“That’s why you see a lot of these body builders and weightlifters have heart attacks young because they’re pumped up so much and the heart can’t take the pressure.”