Former world champion Amir Khan has vowed to concentrate on his training in a return to the United States amid his public split from wife Faryal Makhdoom.

Khan, 30 years old, looked relaxed in shirtless selfie he posted to his Twitter page. His cryptic tweet suggested he wasn’t going to let all the fresh attention to his personal life bother him.

The picture came after he revealed plans to return to the United States and focus on his boxing career. He plans to resume his training with head coach Virgil Hunter.

He posted: "Mid August I’m off to San Francisco to start my training. Putting everything behind me and moving forward. Get back on top with big fights."

Amir recently confessed that he had been having trouble sleeping since his split from Faryal.

The Sunday Mirror reports him as saying: "I haven’t slept all night."

"I don’t know what to say. I’m gutted. I’ve not slept all night. I went to see some people at the marina and I’ve been up all night. I couldn’t sleep. I need time to think. I just need to rest and to speak to some people," he apparently said.

A few days ago, he confirmed the end of his marriage on social media and claimed that his wife had moved on to dating heavyweight king Anthony Joshua, who denied the allegations.

Khan has been out of the ring since May of 2016, when he was knocked out cold by then WBC middleweight world champion Saul "Canelo" Alvarez at the T-Mobile Arena in Las Vegas. Khan was initially going to face Manny Pacquiao on a date in April, but those plans fell apart after the claimed investors were unable to come up with the necessary funds to stage the even in the UAE.