Germany's Justice Minister Heiko Maas suggested that the New Year's Eve violence, of which the Cologne Police have recorded 516 cases till Sunday, 10 January, had been coordinated.
Sunday's number of 516 cases in cologne alone was a sharp increase from the 379 cases on Saturday there; Hamburg has reported 133 cases of sexual assault as well.
"For such a horde of people to meet and commit such crimes, it has to have been planned somehow," Germany's Justice Minister Heiko Maas told Bild am Sonntag newspaper in an interview. "No one can tell me that this was not coordinated or planned. The suspicion is that a specific date and an expected crowd was picked," he said while speaking about Cologne.
In Cologne, 40% of the cases recorded were sexual assault charges.
Similar cases of sexual assault, including groping and intimidation, besides pickpocketing, have been reported from across German cities like Berlin, Stuttgart, Duesseldorf and Frankfurt.
Other European countries like Finland, Sweden and Austria have also witnessed an increase in sexual assault cases on New Year's Eve, which has led to warnings being issued to women in some cities asking them not to step out alone at night, reported Daily Mail.
Many asylum-seekers have been identified as suspects in cases across Germany, which had taken in 1.1 million refugees, putting pressure on German Chancellor Angela Merkel, who had so far had an open-door policy for asylum-seekers.
On 9 January, Merkel, who has been criticised by opponents over her refugee-friendly policy, took a strong stance condemning the attacks and pushing for changes in deportation laws for asylum-seekers who are convicted of crimes. A change to the existing rape law is also being discussed in Germany, which would include cases of molestation and groping.
"If the law does not suffice, then the law must be changed," she said.
"Cologne has changed everything, people now are doubting," AFP quoted Volker Bouffier, vice-president of Merkel's CDU party, as saying.
The recent incidents have led to outrage among the masses. On Saturday, 9 January, in Cologne, while women took to the streets to demand improved security measures, anti-immigration groups tried to capitalise on the issue since some asylum-seekers have been accused of mass violence on New Year's Eve. On the other hand, anti-fascist protests broke out to rival the anti-immigration protesters, which led to clashes and water cannons being sprayed on the crowd by the Cologne police.