Drugs and a stun gun have been found on board Justin Bieber's tour bus, according to Swedish police.
Police spokesman Varg Jyllander told Sky News an officer on crowd duty smelled marijuana from the vehicle.
It had been parked outside the Stockholm hotel where the pop star was staying just before his concert in the capital on Wednesday night.
Mr Jyllander said drugs police were alerted and followed the bus to the venue before searching the empty vehicle after around 10 passengers - including Bieber - had entered the arena.
He explained: "They found a small amount of drugs and a stun gun.
"Now the drugs are (being) sent over to the forensics lab, and before we have the analysis results we won't (comment further). It was a short search for around half an hour.
"There is no suspect at the moment. The crew left and took the bus, but the investigation is still going on.
"It was a small stun gun and in this country you need a permit to carry one or have one - and they hadn't."
He said testing the drugs was "not a high priority" and it could be some days before the results are known. Mr Jyllander added that the singer and his entourage were free to leave the country.
Bieber is travelling around Europe on his Believe tour and is due to perform in Finland on Friday.
He tweeted after arriving in Helsinki ahead of the show: "Some of the rumours about me....where do people even get this stuff. whatever...back to the music."
The 19-year-old Canadian star's tour has been controversial.
He was criticised earlier this month after visiting the Anne Frank Museum and saying he hoped the young Holocaust victim would have been a "belieber" - one of his army of fans.
Last month, Bieber's pet Mally, a 17-week-old capuchin monkey, was seized in Germany after he failed to produce the correct paperwork.
He was also pictured walking bare-chested through customs in Poland and was reportedly asked to leave a top hotel in Paris.
The star also apologised for appearing on stage late during a run of shows in London - and was caught on camera "struggling" during another concert.