A bus associated with the current Justin Bieber concert tour was found to have marijuana and drug paraphernalia on it, border officials in the U.S. have confirmed.

On Sunday, U.S. Customs and Border Protection officers stopped the bus which was trying to enter the U.S. via the Ambassador Bridge, which connects Windsor, Ont., to Detroit.

"During the secondary inspection, a K-9 alerted to the presence of drugs and a subsequent search of the bus revealed marijuana and drug paraphernalia," the agency said in a statement.

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Mr. Bieber, who held a show later that evening in Detroit, was not on the bus, border officials said.

The border patrol added that officers seized the marijuana and paraphernalia and issued a penalty to the driver. The bus and passengers were released without further incident.

The 19-year-old pop star, who held two shows in Toronto last week as part of his Believe tour, has garnered a significant amount of negative attention over the last few months.

In April, numerous media outlets reported that Swedish police found a small amount of drugs and a stun gun on a tour bus used by Mr. Bieber.

And earlier this month, a video went viral that showed what seems to be Mr. Bieber urinating into a mop bucket in a restaurant kitchen while his friends and someone who looks like security stand by and watch.

Mr. Bieber's Believe tour is currently on its second North American leg. The tour wraps up in Atlanta in August.