The contest in Oberhausen saw Sturm triumph by a majority decision to win the World Boxing Association (WBA) super middleweight belt in a rematch of the fight from May 2015, won by Chudinov.

Sturm’s victory also saw him become the first German to be a world champion five times at professional level.

He had previously held the WBA and World Boxing Organization (WBO) middleweight titles.

The 37-year-old has now confirmed his positive test, which could see him stripped of the belt.

“I got a notice that on 20.02.2016 in my fight against Fedor Chudinov I tested positive in doping control, more precisely, it is in my body, revealing the presence of 3'-hydroxy-stanozolol glucuronide, or substances to increase muscle mass and weight,” the boxer of Bosnian orgin, whose real name is Adnan Ćatić, wrote on Facebook.

“Since the practice to publish the results of doping controls most after two or three weeks, I was very surprised that I was only after eight weeks of testing was informed that I was positive on the test.

“In my 26 years of professional boxing, more than a hundred times I exercised various doping controls (urine and blood) and each of the doping control was negative, whether it is on the announced or unannounced controls.”

“I promise you, everyone, for your personal dignity, but also dignity all over Bosnia and Herzegovina and Germany, I'd do anything to prove I'm clean.”

Sturm has already claimed that he will request the B-sample to be tested, with the 37-year-old facing the prospect of a two-year ban if the positive test is confirmed.