Anthony Joshua has pledged to stop boxing if he ever fails a doping test – and says he would rather lose a fight than take banned performance‑enhancing drugs.

The WBA, IBF and WBO heavyweight champion’s comments came after a press conference at Wembley with his next opponent, Alexander Povetkin, who has twice been banned for taking the prohibited substances meldonium and ostarine.

“I would rather take a loss than be done for doping, because that is worse for your legacy than taking a loss,” Joshua said. “Weigh it up. Dope, be banned, legacy damaged – or accept that someone is better than you on the night, give them the respect and bounce back. I would rather stay clean and give it my best every time.”

Joshua, who said he had been tested twice for his fight against the Russian on 22 September, also revealed he pays £30,000 to be tested by the Voluntary Anti-Doping Association in addition to the UK Anti-Doping Agency.

However, he insisted he had no problem facing Povetkin, who won gold in the super heavyweight division at the 2004 Olympic Games and went on to hold a WBA world title for almost two years before his only professional defeat, against Wladimir Klitschko, in 2013, despite his previous bans.

“When he is fighting me it will be a straight and clean fight,” Joshua said. “His past is his past and they dealt with it however they did. But if I got done for doping – it would never happen – then they would deal with me. I know I would never be able to box again because I would be made an example of.

“I am on Ukad and Vada, £30,000 every time for each fight. They know your whereabouts every day. After the Joseph Parker fight I had two drugs tests at the same time because the two organisations don’t work together. It is annoying but it is needed for clean sport.”

Povetkin, who failed a test for meldonium days before he was due to fight the WBC champion Deontay Wilder in May 2016 and for ostarine seven months later before he was due to fight Bermane Stiverne for the interim heavyweight title, insisted he had never used banned drugs.

“I know that I am clean,” he said. “First, I was caught on meldonium, and it was a nanogram quantity. But I was clean a couple of tests before it and I was clean when tested after that. For me it was very, very suspicious.

“The second time, ostarine. First, I don’t know what it is. Second, I read about it and they said it is for gaining muscle. I only weighed 100kg for that fight. The couple of tests before I was caught were clean. The tests after were clean. And the time they found it, the time before the fight, was very, very minor in quantity. Doesn’t it all sound a little suspicious?”

The 38-year-old also claimed he was annoyed that so many Russian sports stars had been accused of being part of a state-sponsored doping programme.

“I don’t think that our sportsmen in Russia consume all those things they are accused of. It’s a bit annoying, to be honest. As an amateur on the Russian team I understood myself what we were consuming and what we were taking, and I can assure you there was nothing prohibited.”