Nutso on a paparazzo! “Rough week” JUSTIN BIEBER out of control as he explodes in a torrent of RAW HATE in UK smackdown!

The morning after Bieber "collapsed" onstage during his show at London’s O2 Arena and was rushed ro the hospital, the pop twerp  went nutso on a paparazzo hanging outside his London hotel.

The pap was trying to get a shot of the Canadian singer, 19, as he left his hotel, and claimed he was knocked around in the stampede rush of people surrounding the mega-star.

While Bieber rushed into his SUV flanked by two burly bodyguards, the pap began cursing at the muscled beefcake saying they should “F**k off back to America,” then calling the singer a “F**king little moron.”

Suddenly, a raging Bieber leapt out of the vehicle and returned verbal fire with the cameraman, asking, “What the f**k you say?”

“You heard what I said,” the pap said. “You heard what I f**king said, mate.”

Bieber shot back, “I’ll f**king beat the f**k out of you,” and threw a wild punch the air.

“F**k you little c**k,” the photog responded.

RadarOnline reported Bieber tweeted : “Ahhhhh! Rough morning. Trying to feel better for this show tonight but let the paps get the best of me,” and “Sometimes when people r shoving cameras in your face all day and yelling the worst thing possible at u…well I’m human. Rough week.”

Thus spake Justin Bieber- headline maker.