Throngs of teens, most of them girls, have prowled the streets of the capital in the hopes of catching a glimpse of their hero ever since he arrived at Gardermoen airport on Tuesday as part of a tour to promote his latest album.
In a Twitter message posted shortly after 2pm, Oslo police confirmed the rumour that the pop star was planning to put on a show in the city.
”Bieber is expected to put on a concert from a stage in the water outside the opera house this evening at around 9 or 9.30pm," police wrote.
According to a schedule spotted by a Scanpix photographer in a car outside the Hotel Continental where Justin Bieber is staying, 5,000 tickets will be made available to fans on a first come, first served basis.
True Beliebers, as his fans are often known, had already begun gathering on the roof of the opera house on Wednesday morning as rumours of the concert and its location gathered force.