Friends worried Justin Bieber is 'heading for a breakdown'

Justin Bieber's inner circle are reportedly concerned the pop star is heading for a breakdown.

The Sorry singer has been displaying increasingly erratic behavior in recent months, including banning fan selfies because he feels like "a zoo animal", halting meet-and-greets backstage on tour and being spotted walking barefoot in a park last month (May16).

Concern ramped up on Wednesday, when he was involved in a fist fight with Cleveland, Ohio local Lamont Richmond outside a hotel. Video footage appears to show them exchanging blows before Justin is thrown to the ground and the fight is broken up.

Those close to the pop star, 22, are reportedly "nervous" around him and are worried that he is overwhelmed by his fame, burnt out by his busy tour schedule and heading for a breakdown.

"He feels like people forget that he is a human being and needs privacy," the source told ETOnline.com. "Him writing those social posts about the 'no photos etc…,' that is him just being overwhelmed. It wasn't intended to make people think he is a snotty pop star, but it's definitely reflective of what he is going through right now.

"During his time off, he has been trying to be as normal as possible and trying to be super low-key about everything... The situation is serious and no one is taking it lightly. Justin is extremely burnt out and just needs a break."

An eyewitness of the fight tells the website Justin was "on edge" while standing outside his hotel because he was "getting harassed".

Lamont posted a video online explaining that he simply asked Justin for his autograph and a picture. He tells TMZ.com the pop star, who was allegedly drunk, swore at him and threw the first punch. According to the website, Lamont has met with a lawyer to discuss civil action.

Justin reportedly referenced the incident on social media by boasting, "Not a scratch on this pretty boy" alongside selfies. However, the post has since been deleted.