(CNN) -- Swedish police found illegal narcotics on Justin Bieber's tour bus as it was parked outside Stockholm's Globe Arena, where he was performing, a police spokesman said Thursday.
While a source close to Bieber insisted it was a non-story and no charges were filed, it is the latest stumble in the teen pop star's European tour. Bieber's publicist had no official comment when contacted by CNN.
Police found a small amount of unspecified illegal narcotics on the tour bus that Bieber and about nine others had taken to the arena for the concert Wednesday night, Stockholm police spokesman Varg Gyllander said.
Authorities searched the bus at the arena after a police officer smelled marijuana near the vehicle when it was outside a Stockholm hotel, Gyllander said. The Bieber team had left the bus before police searched it.
The case is under investigation, but no arrests were made and no charges have been filed, Gyllander said. For a charge of possession of narcotics, police must find the drug on the offender, he said.
The Stockholm concert proceeded as scheduled. Bieber's next concert is on Sunday in St. Petersburg, Russia.
Earlier this month, Bieber drew criticism for a remark he left in the guest book of the Anne Frank House in Amsterdam, Netherlands. He suggested that Frank, the teenage diarist who died in a Nazi concentration camp in 1945, would have been a fan of his. Critics accused him of being narcissistic, but others, including Frank's stepsister, criticized the uproar and said Frank might indeed have been a fan.
And last month in Munich, German authorities confiscated a young monkey that Bieber traveled with.
CNN"s Stephanie Halasz and Jason Hanna contributed to this report.