Alexander Povetkin
Russia's Alexander Povetkin is a former WBA world heavyweight championEpsilon/Getty Images

Alexander Povetkin's WBC world heavyweight title challenge against Deontay Wilder on Saturday 21 May has been officially postponed after he failed a drugs test. The Russian boxer, a gold medal winner at both the Olympic Games and World Championships as an amateur, tested positive for traces of meldonium back in late April.

The drug, manufactured in Latvia and used to treat ischaemia and increase blood flow, also caused the failed test and subsequent provisional suspension of five-time tennis Grand Slam winner Maria Sharapova earlier this year. It was added to the World Anti-Doping Agency's (Wada) banned list in September 2015, a decision which officially came into effect back in January.

"Keeping the priority of safety and also the principle of justice, the WBC will continue the investigation into the case," WBC president Mauricio Sulaiman said in a statement to confirm the organisation's decision. "Consequently, the event scheduled for May 21 in Moscow is hereby officially postponed."

Povetkin, a former WBA (regular) champion who has won 30 of his 31 professional fights with 22 knockouts and suffered the only defeat of his career to date against Wladimir Klitschko in 2013, said:"I'm clean. I haven't taken anything or consumed anything, so I've got nothing to fear. I'm getting ready for this fight and we're not looking at anything else."

According to AP, the 36-year-old claims to have taken meldonium before it was banned. Promoter Andrei Ryabinsky declared himself "disappointed to lose time" preparing for a fight that he clearly believes his man can win. He also reportedly claimed that three of Povetkin's four doping tests were clean.

It remains to be seen if the bout will be rescheduled pending the outcome of an ongoing WBC investigation. Alabama native Wilder, who has retained his belt on three separate occasions since outpointing Bermane Stiverne 16 months ago, was due to travel from the United States and make his fourth defence at the 14,000-capacity Megasport Arena in Moscow.

"I'm very disappointed that due to Povetkin's failed drug test the fight is not going to happen on May 21 in Moscow," the "Bronze Bomber" said. "I had worked very hard to prepare myself for this important title defence, spending the last two weeks training in England to get accustomed to fighting in Europe.

"I wanted to give the fans a great show, but we understand the WBC's position that the fight occur on an even playing field. This is a huge disappointment and a setback to my goals in boxing. I want to be an active heavyweight champion and it is still my goal to collect all the belts and become the undisputed heavyweight champion of the world."