Pop star JUSTIN BIEBER has blamed his London meltdown on his punishing schedule, insisting gruelling daily workouts, homesickness, and the strain of performing live took a toll on him.

The Baby singer hit headlines around the world on Friday (08Mar13) when he was filmed in a foul-mouthed clash with a paparazzo in the U.K. capital.

The incident came after days of mounting pressure on the teen star, who was criticized for turning up late for his opening gig at London's O2 Arena on 4 March (13) and had a bust-up with bouncers at a nightclub as he celebrated his 19th birthday on 1 March (13).

His 10-day trip to Britain ended in chaos and controversy on Friday when Bieber was caught on camera threatening to "beat the f**k out of" a snapper outside his London hotel, but now the Canadian star has spoken out, blaming his behavior on a "hard" few days.

He tells German newspaper Bild, "It was a hard week. I was working out every morning and had a huge show every night. When people are pushing their camera in your face all day long and yell mean things at you (it's hard). I'm only human, too. I'm far away from home, I miss my family, my siblings and my friends."