Junior welterweight champion Lamont Peterson is refusing to bow to calls from Amir Khan to surrender his IBF and WBA titles.

The American was due to meet Khan on May 19 in a rematch of their light-welterweight clash, which Peterson won by controversial circumstances in December.

However, Peterson failed a drugs test after testing positive for a synthetic testosterone, forcing the Las Vegas meeting to be cancelled.

The 28-year-old insists he had a testosterone pellet inserted in his hip for medical reasons and there was no intention to gain an advantage. And he says the doctor never informed him that the procedure would trigger a positive drug test result.

His case will be discussed by the Nevada State Athletic Commission in June and until they publish their findings Peterson says he will not be giving up his titles.

He said: "Let the commission decide, let the sanctioning bodies decide. Until that point I'm still the champ. I've never been a cheat. I don't like it when people cheat. It's just my word but the pellets didn't do anything to help me beat him."

"If the procedure I done is what gave me the dirty urine, then what else can I say? I made a mistake. That's all I can say. apologize for it and try and move on with my career. But I think it's wrong for anyone to call me a cheat."