The alleged incident occurred on Sunday at a shopping center near Bieber's home in Calabasas, northwest of Los Angeles, as the lensman tried to take pictures of the singer and his actress girlfriend Selena Gomez.

"Singer Justin Bieber and actress Selena Gomez were at The Commons at Calabasas shopping center," said spokesman Robert Wiard of the Malibu/Lost Hills sheriff's station.

"As the victim attempted to take a picture of Mr. Bieber, Mr. Bieber and the victim were involved in a physical altercation," he added.

The 30-year-old photographer, whose identity has not been revealed, called 911 and requested sheriff's deputies and paramedics.

He complained of pain in his upper torso and was taken to a hospital where he was treated and released, Wiard said.

Bieber left the scene before deputies arrived, the spokesman added, saying that detectives planned to interview other witnesses and the Canadian singing sensation about the incident.

The TMZ celebrity news website said Bieber could not immediately be interviewed because he was in Norway.

Coincidentally, Bieber was pictured "training" with former boxing champion Mike Tyson days before the alleged incident, the Huffington Post reported, quoting Tyson as tweeting alongside an online video: "JB's got the moves!"