Chancellor Angela Merkel said Thursday Germany must have a "fundamental" debate about how to integrate newcomers, as police identified 16 people suspected of a shocking rash of sexual assaults blamed on migrants.
As outrage grew over the assaults, which included two alleged rapes and several accounts of groping during New Year's Eve festivities in Cologne, Merkel said citizens were right to raise serious questions.
She pledged strong action and stressed that "we must also speak again about the cultural fundamentals of our co-existence".
Some 121 complaints have been filed so far, with police saying they are investigating "16 young men... mostly of North African origin" although no one has yet been charged.
Investigators are trawling through CCTV footage and examining witness accounts to determine whether the suspects were implicated, police added.
About three-quarters of the cases involved sexual offences, while others related to theft or bodily harm.
Welcoming the fact that large numbers of alleged victims have come forward, Merkel said there were "very serious questions that go beyond Cologne" for Germany.
The attacks have shown that there is in "some quarters, contempt for women," she said.
"We need to confront that with utmost determination," Merkel said, adding that she did not believe that the cases were isolated.
Although authorities have said there are no indications that the perpetrators of the assaults were asylum seekers, critics of Merkel's open-door approach to those fleeing war have seized on the opportunity to draw a link.
With debate mounting over whether to make it easier to expel convicted asylum seekers, Merkel vowed to consider further action.
"We need to re-examine if everything necessary has been done with regards to expulsions to send a clear signal to those who do not respect our law."
But as Merkel pressed for an EU solution to the worst refugee crisis to hit Europe since World War II, the incidents stoked resistance to her policies.
Slovak Prime Minister Robert Fico said that his government would not take any decision, "which would give rise to a distinct Muslim community in Slovakia".
"This is the only way to eliminate risks," Fico added. "We do not want something to happen in Slovakia like what happened in Germany."'Too many at the same time'
The assaults plaguing the Rhineland city during New Year's festivities were not isolated, with the northern port city of Hamburg also hit.
Some 70 complaints of sexual assaults have been filed, Hamburg police said, with 23 of those victims also reporting that they'd been robbed.
Witnesses in Cologne said groups of 20-30 young, intoxicated men out of a crowd of about 1,000 people had surrounded victims, assaulted them and in several cases robbed them.
On Thursday, Bild newspaper and Spiegel Online quoted an internal police report detailing how officers were powerless to hinder the terrifying rampage on New Year's Eve.
"The officers were unable to prevent all events, assaults, crimes -- there were just too many at the same time," according to the police report.
Both victims and witnesses were threatened, it said, describing unaccompanied women as "running a veritable gauntlet of heavily drunk men in a scene that was indescribable".
Interior Minister Thomas de Maiziere warned that foreigners who commit serious crimes "must assume they will be deported", including asylum seekers even though there are strict laws surrounding their expulsion.
German law requires a conviction of at least three years in prison before an asylum seeker can be forcibly returned while his or her application for refuge is being examined.
The individual must also not face threats in his or her country of origin.
But de Maiziere said: "We will have to discuss if we should change" these rules that are in line with the UN Geneva Convention and European Human Rights Convention.
But the Social Democrats, junior partners in Merkel's left-right "grand coalition", argued against any changes to the law.
The SPD's deputy chief, Ralf Stegner, told Die Welt newspaper that "we need neither changes to fundamental rights for asylum nor to the Geneva Convention on refugees."
He also warned that constantly "reacting to current public moods is not a responsible manner of governance."
In a bid to calm tensions, Justice Minister Heiko Maas said that asylum seekers with convictions of one year can already be expelled -- although a grace period must be given to the individual to leave German territory on his own accord, failing which he would be forcibly returned.