German Chancellor Angela Merkel has said she is considering changing the law to allow immigrants who commit crimes to be expelled from Germany faster, it has been reported.
And police in the Swiss city of Zurich said about six women had reported being robbed and sexually assaulted on New Year's Eve in attacks "a little bit similar" to those in Germany.
Asylum seekers are now sent back only if they have been handed a sentence of at least three years and the situation in their countries is not putting their own lives at risk.
Cologne officials didn't want to publicize the incident because of its "politically awkward" nature, fearing anti-immigration groups could use the attacks to stir up hatred.
According to reports, earlier today, the German interior ministry said asylum seekers were among those involved in the violence including nine Algerian men, eight Moroccan men, five Iranian men, and four Syrian men.
They have been accused of not dealing quickly enough with the amount of drunk and aggressive people gathered in the square outside Cologne's central train station, where the assaults took place, and failing to respond when the attacks started happening.
Police added that around 40% of the cases relate to sexual assault.
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.
Two male suspects, aged 16 and 23 with "North African roots", who were reportedly detained by police, were later released by the authorities, WDR reported.
The North Rhine-Westphalia state interior minister Ralf Jaeger told reporters he asked the chief to take "temporary retirement" after the violent clashes. According to the German Interior Ministry, almost 1.1 million refugees were registered in Germany in 2015, more than 400,000 of them from Syria.
Cologne, a city of about 600,000 people, accepted more than 10,000 refugees in December alone, but some said they now feared a backlash, with Pegida, the anti-Muslim protest movement, set to demonstrate in the city on Saturday. That's not the case for the mob sex attacks and muggings in Cologne, where police spokeswoman Stefanie Becker told CNN that more than 121 criminal complaints have been filed relating to the mass assaults, including two alleged rapes.
The strike isn't considered to be linked to the events in Cologne, the police statement said.
Members of Cologne's Muslim community, including some who have lived in the city for decades, have joined other Germans in condemning the attacks.
Two asylum seekers have been arrested and more than a dozen others are suspected in connection with the recent attack on women in Cologne, further intensifying an already-heated debate over Germany's welcoming of refugees into its borders.
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