A preliminary toxicology report shows Justin Bieber had Xanax and marijuana in his system when he was pulled over for drag racing in Florida last week.

Teen idol Justin Bieber smoked marijuana and took the anti-anxiety drug Xanax before his arrest in Florida last week, police have said, a day after he was charged over a separate case.

Bieber has pleaded not guilty to charges of drunk driving, resisting arrest and driving with an expired licence for drag racing in a flashy Italian sports car in Florida.

“He was driving with Xanax and marijuana in his system when he was pulled over last week by Miami Beach police,” Sergeant Bobby Hernandez told AFP.

A preliminary toxicology report does not indicate how much THC – found in pot – or key Xanax ingredient alprazolam Bieber had in his system. It turned up negative for illicit drugs such as cocaine, opiates and methamphetamine.

Bieber was tested just after his January 23 arrest, part of a string of bad behaviour from the 19-year-old singer.

He is set to be arraigned on February 14, although he does not need to be present for the proceedings.

Bieber’s father Jeremy meanwhile tweeted a photo saying the pop star was home “safe and sound” after Canadian police charged him Wednesday with the December assault of a limousine driver.

The young heartthrob is due in court on March 10.

In a growing list of run-ins with the law, Bieber’s Los Angeles home was searched earlier this month because he allegedly hurled eggs at a neighbour’s house.

The singer also got in trouble with authorities for spraying graffiti in Brisbane and Brazil, where he was also allegedly involved with prostitutes.

A petition on the White House website calling for the Canadian-born pop star’s deportation had garnered more than 204,000 signatures by 4:30pm Thursday (0830 Friday AEDT).

The number of signatures easily surpasses the 100,000-threshold required for presidential consideration.