The scandal, which followed the leak of an internal memo to the Dagens Nyheter newspaper, is the latest in a ripple effect seen across Europe following the sexual assaults allegedly carried out by asylum seekers in the German city of Cologne at New Years.
The DN said that from the very first day of We are Sthlm, a free festival held last August for 13-19 year olds, police were aware of gangs of young Afghan men surrounding and sexually harassing girls.
In an internal police memo seen by the newspaper, officers identified a group of approximately 50 men, "so-called refugee youths, predominantly from Afghanistan," whom they suspected of being behind the attacks, adding that "several of the gang were arrested for sexual harassment".
Sweden's Prime Minister called for an immediate inquiry into why no crimes were prosecuted and whether police hushed up the assaults. Dan Eliasson, Sweden's national police commissioner, agreed that the offences were "completely unacceptable" and launched an "immediate internal investigation into any wrongdoing or crimes".
German Chancellor Angela Merkel said that Europe had lost control of the refugee crisis, as she confronts public anger.
"All of a sudden we are facing the challenge that refugees are coming to Europe and we are vulnerable, as we see, because we do not yet have the order, the control that we would like to have."
Authorities in Cologne confirmed for the first time that the attacks were "almost exclusively" carried out by men "of an immigrant background". Police have identified 19 suspects so far, including 10 who are in the country as registered asylum seekers.
"As disgusting as the crimes in Cologne and other cities were, one thing is clear: there is no justification for a general agitation against foreigners," said Heiko Maas, the Justice Minister. Some people "appear to have just been waiting for what happened".
Bild claimed that a suspected terrorist who was shot dead trying to attack a Paris police station last week was arrested almost two years ago for sexual assault in Cologne, groping women in a night club.

