Justin Bieber fans are descending on Oslo, Norway in such large numbers in anticipation of his concert there that police are considering declaring a state of emergency.

Bieber is set to perform four songs at Oslo's opera house for his Around The World television special.

The crowds were so massive that the police lost control -- and are pleading with Bieber to take the stage early ... before all hell breaks loose ... as in RIGHT NOW, TMZ reported.

Bieber has taken to the police's suggestion that he warn his fans not to get out of control, tweeting that Beliebers should comply with authorities and not get too wild.

NORWAY - please listen to the police. I dont want anyone getting hurt. I want everything to go to plan but your safety must come first..., the singing sensation tweeted. ...here r the details...at 920 2nite Im going to do a free show 4 u the fans at the Opera House here in Oslo...  ...the show is part of my #AroundTheWorld TV special and I will be doing 6 songs, 4 new, 2 old before i leave. BUT.... ...for the show to happen u must all listen to the police. we are all concerned for your safety and i want what is best for u. please listen and tonight we will have some fun. love you and im excited to see you all. NORWAY...THANK YOU FOR HAVING ME! #BELIEVE.

Bieber ended by graciously thanking his Norwegian fans.

and NORWAY...u are awesome! #BEASTMODE, Bieber concluded.

Justin Bieber's Around The World special is scheduled to air on June 29 NBC from 8 p.m. to 9 p.m. EST.