Swedish police say they have found drugs on board a tour bus used by Justin Bieber.

Police spokesman Lars Bystrom says a small amount of drugs and a stun gun were found when officers raided the empty bus parked under the Globen concert venue in Stockholm, where Bieber was performing Wednesday.

Bystrom said Thursday they have no suspects and no one has been arrested. He declined to identify the drug, saying it had been sent to a laboratory for an analysis.

He says police acted after smelling marijuana coming from inside the bus when it was parked outside the hotel where Bieber was staying. The drug squad was alerted and searched the bus during the concert.

But a source close to Bieber denied the claims made by the police. 

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"The cops found nothing and left. No violations. Nothing," the source told FOX 411. 

On Thursday morning, the 19-year-old singer tweeted: "some of the rumors about me....where do people even get this stuff. whatever...back to the music."

Bieber is in Stockholm as part of a world tour.

The Associated Press contributed to this report.