German police say the number of criminal complaints filed after the events on New Year's Eve in Cologne has risen to 516 - 40% of which relate to allegations of sexual assault.
Police in Cologne investigating the crimes are focussing on people of North African origin, they say.
On Sunday evening six Pakistanis and a Syrian man came under attack in the centre of the western German city.
Angela Merkel's immigration policy has come under criticism since the attacks.
Around 1.1 million asylum seekers arrived in Germany in 2015.
The scale of the assaults on women in Cologne and other German cities on 31 December has shocked the country, and police handling of the events has been sharply criticised.
Riot police used water cannon to disperse anti-migrant protesters in Cologne on Saturday.
The attacks on Sunday took place in the early evening. In the first, a group of around 20 people attacked six Pakistanis, two of whom had to be treated in hospital.
Separately, five people injured a Syrian man who did not need hospital treatment.
The higher figures came as German authorities were urged to find out whether the series of New Year's Eve sexual assaults and robberies in Cologne were linked to similar crimes in other cities.
Justice Minister Heiko Maas told the Bild newspaper on Sunday that he was convinced the attacks were pre-arranged.
"If such a horde gathers in order to commit crimes, that appears in some form to be planned,'' he said. "Nobody can tell me that this was not co-ordinated or prepared."
Authorities and witnesses say the attackers were among about 1,000 people, mostly men, who congregated at Cologne's central train station before breaking off into small groups that molested and robbed women.
Victims described chaos as dozens of sexual assaults and robberies were carried out with little apparent response from the authorities around Cologne station.
Similar attacks to those seen in Cologne were also reported in Hamburg and in Stuttgart on New Year's Eve. In Bielefeld, hundreds of men tried to force their way into nightclubs, Die Welt reported (in German).
Police said several women had alleged sexual assault.
On Friday, the chief of police for Cologne was suspended. Wolfgang Albers had been accused of holding back information about the attacks, in particular about the origin of the suspects.