OTTAWA (AFP) - Toronto's bad boy mayor Rob Ford on Thursday defended troubled pop star Justin Bieber after police in Canada's largest city charged the teenager with assault, his second arrest in a week.

"He's a young guy, 19 years old. I wish I was as successful as he was," Mr Ford told a Washington radio show, urging listeners to "think back" to when they were teenagers.

Bieber was charged Wednesday with assaulting a limousine driver in Toronto last month.

Toronto police accused Bieber of hitting the driver "several times" over the back of the head. The car had picked him and five others up from a nightclub in the city in the early hours of December 30.

The misdemeanor charges in Canada follow his arrest in Miami Beach on January 23 for driving under the influence and resisting arrest during a street drag racing incident.

Through his lawyers, Bieber told AFP he is innocent of the Toronto charges, and he has pleaded not guilty to the charges filed in Miami Beach.

In recent weeks, Bieber's Los Angeles mansion was searched over accusations he hurled eggs at a neighbor's house, and illegal drugs were found at his home.

One of his associates was arrested.

The singer has also gotten in trouble with the authorities in Australia for spraying graffiti. And in Brazil, Bieber was photographed emerging under a blanket from a notorious Rio brothel.

The White House has been asked to weigh in on Bieber's bad behavior after it received a petition with more than 150,000 signatures calling for his deportation.

Mr Ford himself has been mired in scandal for months, after admissions of crack smoking and binge drinking.

Though he defended his fellow Canadian, Mr Ford said he is not a fan of Bieber's music, preferring to listen to Led Zeppelin, the Eagles and the Rolling Stones.