A police officer stands guard at the Rosenbad government office, in Stockholm | JONATHAN NACKSTRAND/AFP/Getty Images Sweden investigates sex assault cover-up About 50 Afghan men were involved in 2014 sexual assaults, according to Swedish media.

In the wake of the German New Year’s Eve sexual-assault scandal, Swedish law enforcement authorities are looking into claims that a gang of mostly Afghan men harassed girls at a 2014 music festival — an incident that initially went unreported by police.

About 50 youths predominantly from Afghanistan, according to sources quoted by the Swedish daily Dagens Nyheter, were involved in sexual assaults involving girls as young as 11 years old. After the incident, Stockholm police reported that "there have been relatively few crimes,” but information leaked to Dagens Nyheter paints a different picture.

The Stockholm police head of communications, Varg Gyllander, said it was wrong not to speak openly about the 2014 attacks at the time, and an investigation is underway into how the communication department handled the case.

"We should have communicated that. I actually do not know why it did not happen," Gyllander told Swedish Radio.

Sweden’s Prime Minister Stefan Löfven said the incident is “a double betrayal” for the women involved and a “big democratic problem” for his country.

“We shall not close our eyes and look away. We need to deal with such a serious problem,” Löfven said.

According to Peter Ågren, head of the festival's police operation this summer, the background of the men could be a reason why police did not initially report the case.

"Sometimes we do not really say how things are because we believe it may play into the hands of the [right-wing party] Sweden Democrats," Ågren told Dagens Nyheter.

Sweden took in around 160,000 refugees last year —more asylum-seekers than any other European country relative to population size. However, it has since imposed checks on people traveling from Denmark.