Police in Cologne have detained hundreds of men "seemingly of African descent" as part of operations to prevent a repeat of attacks in the German city a year ago.

More than 800 complaints have now been filed in connection with assaults and robberies in Cologne on New Year’s Eve that investigators have linked largely to foreigners, German prosecutors said.

The mass attacks on women in Cologne and other German cities on New Year’s Eve have prompted more than 500 criminal complaints, with Cologne investigations focused largely on asylum seekers or illegal migrants from north Africa, police have said.

Cologne’s police chief has been removed amid criticism of his force’s handling of a string of New Year’s Eve assaults and robberies.