German Chancellor Angela Merkel's coalition condemned a "new dimension" of crime after scores of women reported being sexually assaulted as they passed though a group of about 1000 men during New Year's Eve celebrations in downtown Cologne.
About 90 women have reported being robbed, threatened or sexually molested at New Year celebrations outside Cologne's cathedral by young, mostly drunk, men, police said on Tuesday.
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Germans react to attacks on women in Cologne
Police say about 60 women reported being robbed, threatened or sexually molested at New Year celebrations in the western city of Cologne.
Cologne police chief Wolfgang Albers told a news conference officers described the men as looking as if they were from "the Arab or North African region" and mostly between 18 and 35 years old. "We have one complaint that represents a rape," he added.
With Interior Minister Thomas de Maiziere saying the perpetrators were "people apparently with a migrant background", the incident at the city's main train station stoked Germany's debate about how to deal with a record number of asylum seekers as news reports and video of the melee spread.
Residents shouldn't harbour "blanket suspicion" against refugees fleeing to Germany to escape persecution, de Maiziere said on Tuesday.
"This is obviously a new dimension in organised crime," Justice Minister Heiko Maas said in a statement. "All the perpetrators must be investigated and brought to justice. We will not accept these cowardly and abhorrent attacks."
Cologne police have reviewed about 90 criminal complaints from women who described being robbed, sexually harassed and in one case raped as revellers poured into Germany's fourth-largest city from the train station at the foot of its cathedral, police spokeswoman Stefanie Becker said.
Cologne Mayor Henriette Reker held an emergency meeting of city authorities to discuss measures to avoid a repeat.
The scale of the assaults became clear as criminal complaints were filed after January 1 and two suspects have been arrested, Ms Becker said.
More than one million refugees arrived last year in Germany, Europe's biggest economy, the largest number fleeing civil war in Syria. Stephan Mayer, a lawmaker in Merkel's Christian Democrat-led bloc, suggested a possible link to the Cologne events.
Integration commissioner Aydan Ozoguz warned against putting foreigners and refugees, hundreds of thousands of whom have entered Germany largely from Middle Eastern war zones, under "blanket suspicion".
About 150 people gathered in front of Cologne's cathedral on Tuesday evening to protest against violence against women. One of them held a sign saying: "Ms Merkel where are you? What do you say? This scares us!"
"It would be terrible if such crimes were committed by some of those to whom we've generously taken into our country," Mr Mayer, a member of the Bavaria-based Christian Social Union, said in a statement. "If it turns out that the majority of assailants indeed came from Arab or North African regions, that shouldn't be hushed up."
Chancellor Merkel, who is facing criticism from the CSU and her own coalition for declining to cap the number of arrivals, reaffirmed her principled stance in her first public appearance of 2016.
"In our constitution, it says that human dignity is inviolable," she told carol singers at the chancellery in Berlin on Tuesday. "That applies not only to Germans and people who live in Germany" but worldwide, she said.
Justice Minister Maas later told a news conference the assailants were well-organised.
"If a thousand people gather and commit the same violation, then there is some level of organisation involved," he said.
The right-wing Alternative for Germany (AfD), which has gained in polls in part at Chancellor Merkel's expense thanks to a campaign against refugees, said she should close the border.
"Mrs Merkel, is Germany 'colourful and cosmopolitan' enough for you after the wave of crimes and sexual attacks?" tweeted AfD chief Frauke Petry.
Chancellor Merkel told Ms Reker in a phone call the attacks deserved a tough response.
"Everything must be done to investigate those responsible as quickly and completely as possible and punish them, regardless of where they are from," she said, according to her spokesman.
There are almost daily attacks on refugee shelters.
"Events like that in Cologne foster xenophobia," said Roland Schaefer, head of Germany's association of towns and localities.
After a crisis meeting, Ms Reker said new steps would be taken to avoid a repeat, including increasing police numbers at big events and installing more security cameras.
She stressed that women must feel safe at traditional carnival celebrations next month when the city closes down for five days of drunken street parades and parties.
Ms Reker was stabbed in the neck and seriously hurt in October, just a day before she was elected mayor. Police said that attack appeared to be motivated by her support for refugees.
Ms Reker said it was "unbelievable and intolerable what happened on New Year's Eve", but there was no reason to believe those involved in the attacks were refugees.