Amir Khan unleashed a flurry of verbal jabs Tuesday at Floyd Mayweather after the unbeaten American passed him over for a lucrative May 3 bout and chose Argentina's Marcos Maidana.

Mayweather, 45-0 with 26 knockouts, said Monday - his 37th birthday - that he would defend his World Boxing Association and World Boxing Council light-middleweight crowns against Maidana, 35-3 with 31 knockouts, and not Khan.

The 27-year-old Englishman Khan - who defeated Maidana in 2010 - made his fury clear in a statement released by his promotions company and linked to a post on his Twitter feed, intimating that Mayweather was running scared.

"Despite having signed my part of the agreement to fight Floyd in early December, I've been preparing myself for some time that the match-up with him wasn't going to happen," Khan said. 

"Therefore this announcement (Monday) did not come as a surprise.

"I am, however, very disappointed with Floyd and his team for not providing any explanation as to why he delayed the announcement for so long and ultimately avoided the fight with me.

"Clarification, if he was not fighting me, would have allowed me to look over my options and pursue another path, rather than the ultimate delay to my career this has caused."

Khan, 28-3 with 19 knockouts, has not fought since last April 27 and skipped a planned December bout with US southpaw Devon Alexander for the International Boxing Federation title in anticipation of a big-money showdown with Mayweather.

Instead, it has been a major aggravation and the longest layoff of his career, as he attempts to get back on track after two devastating defeats against Lamont Peterson, in 2011, and then Danny Garcia the following year. 

"It has been a very frustrating period as I had been due to fight in December," said Khan, who even won an online poll set up by 'Money Mayweather' asking his fans to decide whether he should face the Englishman or Maidana.

"I was strongly advised to not take this fight (Alexander) as I would be facing Floyd this May - and therefore signed my side of the contract on this belief.

"Floyd was keen to engage with the fans and so decided to let them choose who he should fight in his next bout. 

"I clearly won his official poll, by a significant margin, but for unknown reasons he decided to ignore the fans' vote and failed to keep his word, disappointing many fight fans who took the time to vote."

Khan said he was hoping to announce details about his next fight within 10 days.

"I've been training very hard since my last fight. I'm a fighter who wants to face the very best out there and have never ducked any opponent," he said.

"I'm focused and ready for my next outing."