Amir Khan has Tweeted that his fight against Lamont Peterson, scheduled for May 19, is officially off after Peterson tested positive for synthetic testosterone.

Khan blamed Peterson and said he is looking for an opponent for June 30.

The Tweet: “The fight is off! sorry everyone the only person to blame is @kingpete26 I’ll be looking for a opponent to fight June 30th.”

Richard Schaefer, the CEO of Golden Boy Promotions, which represents Khan, says thousands of fans were let down by Peterson’s actions and inactions.

“There were 4,000 tickets sold for this event, and many were from England, so it’s very unfortunate for those fight fans who made flight arrangements and many of whom had non-refundable tickets,” Schaefer told RingTV.com on Wednesday evening.

“I feel bad about that. Everyone does. The fans, Khan, the Mandalay Bay, HBO, the sponosors, were all looking forward to this fight. Peterson didn’t give us a chance to salvage the event by the fact that he and his team did not communicate with us when he learned that he failed the test in April.

“It’s unexplainable. And now Peterson has no license.” 

Peterson, who says he underwent a testosterone treatment to deal with chronic fatigue last November, had an opportunity to plead his case to the Nevada State Athletic Commission during a special hearing on May 15, in which the commission would rule whether or not to grant him a boxing license in the state. That, however, was cutting it too close for comfort, according to Schaefer.

“Waiting until next week to know if he could get one didn’t make sense,” he said. “The fact is he should have let us know if he had any medical condition before the contract for this fight was signed. He had another opportunity to come come clean when he learned that his test came up positive.

“If he was so fatigued all the time, why would he get on a plane and fly six hours to Las Vegas to have a testosterone treatment — just one month before he was to fight Khan the first time — when there are quality medical facilities that he could have gone to in his hometown of Washington, D.C.?

“There are lots of questions, a lot of things that Amir and us are scratching our heads about.”

Schaefer says he will sit down with Team Khan tomorrow (Thursday) to discuss when Khan will fight next.

“Whether it’s June or July, we want him back in the ring sooner rather than later.”

BRONER TO HEADLINE JULY 21 BOXING AFTER DARK

Schaefer also told RingTV.com that undefeated 130-pound titleholder Adrien Broner, who was scheduled to defend his WBO belt against the UK’s Gary Sykes in the HBO-televised co-feature to Peterson-Khan II, will likely headline an HBO Boxing After Dark show in his hometown of Cincinnati, Ohio on July 21.

Schaefer said Broner (23-0, 19 knokckouts) would not face Sykes, but rather Vicente Escobedo, provided the 2004 U.S. Olympian beats Juan Ruiz on Saturday.