Bieber -- flanked by bodyguards -- was leaving the Central London hotel moments ago and in the mad scramble to his SUV, he made contact with a waiting photog. The photog -- clearly upset by the physical contact -- immediately claimed he was assaulted and began to cuss out Bieber, who was already inside the waiting SUV.
But Bieber clearly heard the photog's insults ("fuck off back to America", "fucking little moron") 'cause the singer opened his SUV door and sprung out of the car trying to attack the photog. While Bieber's bodyguard held him back, the singer screamed, "What the fuck you say?" The photog shot back -- "You heard what I said ... you heard what I fucking said, mate." Bieber replied, "I'll fucking beat the fuck out of you."
Justin tried to swing at the photog, but his bouncers kept the singer at bay and eventually pushed him back inside the SUV.