While SA boxing is rocked by the WBC's announcement that IBO cruiserweight champion Kevin "Two Guns" Lerena has returned a positive test for a banned substance, the 26-year-old lefty said he was not too worried.

The WBC revealed yesterday that Lerena had tested positive on October 18 in Johannesburg.

The former jockey, who first fought in 2011, said: "I believe there is gross contamination of medication. It is not performance enhancers.

"Look, my promoter Rodney Berman is communicating with the WBC regarding this."

Berman has written a strongly worded response to the Voluntary Anti-Doping Association, who conducted the test.

"What is most perturbing is the fact that without giving Lerena the benefit of a prior explanation, you have insensitively and unfairly made your findings public, which can only cause damage to Lerena's good name and reputation," Berman wrote.

"In the circumstances a public apology would be appropriate with the same exposure and in the same media as your report [was] published."

He added: "The reality is that Kevin is not in training. What would he be doping for?

"He doesn't deserve to have his career tarnished this way."

Lerena, who won the WBF Africa title in 2013, WBC Youth Silver belt in 2014, SA title in 2015, WBA Pan African title in 2016 and IBO belt last year, had a shoulder operation in March.

It was announced that he was to have arthroscopy on his shoulder on July 18, followed by a routine operation.

But the scope revealed that the damage was worse than expected, with tears to Lerena's labrum and rotator cuff, requiring major surgery.

The boxer has a single defeat in 22 fights, with nine knockouts.