The sex mobs committing assaults en masse in Cologne this New Year’s Eve were coordinated or planned, and may have been linked to similar attacks seen across Germany and continent, the police and a German minister have said.

“For such a horde of people to meet and commit such crimes, it has to have been planned somehow,” Heiko Maas, the federal justice minister and a social democrat told Bild am Sonntag.

“No one can tell me that this was not co-ordinated or planned.”

Police began examining internet forums and chat groups last week on the working assumption that it is unlikely hundreds men just met by accident. Pieces of paper have since been found on some of the suspects, with Arabic and German translations of phrases such as “big tits” and “I want to fuck”, indicating a degree of planning.

Over the weekend Cologne police said that officers had recorded 516 cases of New Year’s Eve violence, 40 per cent of which were of a sexual nature including two rapes.

Nearly all of the men involve in the attacks were migrants, Germany’s interior ministry said today. The majority have already been confirmed as recently arrived refugees.

“Based on testimony from witnesses, the report from the Cologne police and descriptions by the federal police, it looks as if people with a migration background were almost exclusively responsible for the criminal acts,” Ralf Jaeger, interior minister from the state of North Rhine-Westphalia.

Police in Hamburg are investigating 120 crimes of a similar nature in the St Pauli neighbourhood, and sexual assaults have been reported in “every major German city” as well as in Sweden, Finland, Austria and Switzerland on New Year’s Eve.

“All connections must be carefully checked,” Mr. Maas added. “There is a suspicion that a particular date was chosen with expected crowds. That would then be a new dimension.”

The federal criminal office has also bee reported as drawing up measures to tackle ‘taharrush gamea’ in Europe, the phenomenon of mass sexual harassment by mobs of young men which is well known in the Arab world, especially Egypt.