LOS ANGELES: The much-anticipated rematch between Lamont Peterson and British boxer Amir Khan has been cancelled after the American failed a drug test, Golden Boy Promotions announced on Wednesday.

Peterson and Khan had been due to fight on May 19 in Las Vegas, after the American took the WBA and IBF light-welterweight titles in December in a controversial split decision.

But Golden Boy said Peterson's failed drug test -- reports said he tested positive for synthetic testosterone -- combined with the Nevada State Athletic Commission's inability to hold a hearing in time led to the fight's demise.

“A failed pre-fight drug test administered by the Voluntary Anti-Doping Association (VADA) coupled with the Nevada State Athletic Commission's legal inability to hold a formal hearing on the matter of licensing Lamont Peterson .... has forced the cancellation of the event,” Golden Boy said in a statement.

Khan reacted strongly to the news, putting the blame squarely on Peterson's shoulders. “The fight is off! sorry everyone the only person to blame is @kingpete26 I'll be looking for an opponent to fight June 30,” he said on Twitter.

Both Khan and Peterson had agreed to random testing by VADA ahead of the rematch.

Peterson won their first bout in Washington in December by a score of 113-112 on two judges' scorecards while the other had Khan a 115-110 winner.

Following the fight, the British boxer -- who won an Olympic silver as a 17-year-old in 2004 -- claimed a “home-town decision” had robbed him of victory. The World Boxing Association ordered a rematch, saying it should take place within 180 days.

Referee Joe Cooper unfairly deducted two points off Khan's scores during the fight for excessive pushing, and also failed to give Khan credit for a knockdown in the first round, the WBA said.

Peterson's publicist Andre Johnson said in a statement to RingTV.com earlier in the week that the boxer's camp was mystified by the test results.

“Team Peterson is very disappointed and distraught by the decision to cancel the May 19 rematch against Amir Khan,” a statement released by Peterson’s team said.

“This is an extremely difficult decision to accept.”

Peterson underwent medical tests and was examined by doctors this week in hopes of providing data to the Nevada State Athletic Commission ahead of the fight in Las Vegas.

“As a condition for this rematch Lamont demanded that Olympic-style random drug testing be implemented,” the statement said. “He has been a true advocate for making boxing drug free and fair.

“In his 18-year career (10 amateur and 8 professional) Lamont Peterson has never failed a drug test and has always complied with the rules beyond this isolated and explainable occurrence.

“We still stand behind the fact that he did nothing wrong and he was more than ready to go through with the May 19 fight.

We will vigorously pursue the truth with regards to this matter and continue to fight to protect this young man's character, credibility and all he has accomplished. Once all the facts have been reviewed we have no doubt that he will be vindicated.”

Peterson won their first bout in Washington, Peterson's hometown, last December but referee Joe Cooper controversially deducted two points from Khan for excessive pushing.

Without those deductions, the fight scoring would have resulted in a draw and Khan would have kept the crowns.