The arrest of five Afghan and Pakistani men immediately stoked calls for the creation of a national police sex-crimes unit. Oslo mayor Fabian Stang also called for discussions on a possible curtailment on freedoms for asylum seekers.

The mass attack on the 16-year-old girls braving the station area after dark was reported just hours after hundreds took part in a torchlight protest to “take back the night”, a rally by women’s groups and ordinary citizens for action against sexual assault.

In all, newspaper VG chronicled five rapes over the weekend, including one in which assailants were described as “Scandinavian in appearance”.

Whatever the count of foreigners involved, Mayor Stang weighed in with a call for “dramatic action” after a record year of 48 “after hours” rapes. While he singled out non-western foreigners, he also made it clear that asylum seekers should not be kept confined from the rest of society.

“But in an extreme situation like the one we are now experiencing, we have to be able to discuss adjusting our principles to protect our girls,” Stang told newspaper Aftenposten.

Another newspaper spotlighting rape reported that police numbers show a minority of attackers have been “non-westerners”. Most of 2011’s attackers have not been identified.

“In 2008/2009, we identified 13 assailants behind 35 attacks,” police inspector Hanne Kristin Rohde told Dagbladet.

“Six of those had at some point been asylum seekers and had either received a 'Yes' or 'No' (to residency status)."

Norwegian Directorate of Immigration director, Ida Børresen, meanwhile, said it was worrying that asylum seekers and criminals were being talked about in the same breath.

“That the majority of culprits are described as “non-Nordic” does not mean that they are asylum seekers,” Børresen was quoted by broadcaster NRK as saying.

Under intense public scrutiny since July 2011, when police mobilization became an issue, police have put 20 extra officers onto the capital’s streets in an effort to curb a wave of rapes since the summer.