Members of the far-right anti-immigration group Pegida, carrying versions of Germany's imperial war flag, protest in Cologne at the weekend

New Year’s Eve violence, thefts and sexual assaults on women in Cologne were “planned” and most of the offences were carried out by asylum seekers or illegal migrants, according to German police and the justice minister.

Heiko Maas, the federal justice minister and a social democrat, said yesterday that the police had evidence the attacks were organised on social media, mobilising young North African men from France and Belgium to travel to the western German city.

“For such a horde of people to meet and commit such crimes, it has to have been planned somehow,” he told Bild am Sonntag. “No one can tell me that this was not co-ordinated or planned.”

It has also emerged that the man who attacked a police station in