ZURICH (Reuters) - About six women in Zurich have reported being sexually molested and robbed during New Year’s Eve celebrations after being surrounded by groups of men, police said in a statement on Thursday.

Zurich police said the attacks resembled incidents in Germany on the same evening but that they did not know of any concrete links between the cases.

About 90 women reported being robbed, threatened or sexually molested at New Year celebrations outside Cologne’s cathedral by young, mostly drunk men, police there said.

Additional incidents, but on a lesser scale, have been reported in Hamburg.

Zurich police said initially there were about 24 separate reports of theft at celebrations along the city’s lakefront. Follow-up investigations showed several cases involved women being fondled on top of their clothing, they said.

A total of about six women now say they were sexually assaulted after entering a “crowd of multiple men with dark coloured skin,” police in the biggest Swiss city said in the statement on Thursday.

In Germany, police described the suspects as looking from “the Arab or North African region”.

Racial tensions are on the increase in Germany and in other parts of Europe due to an unprecedented influx of refugees and migrants in the past year, many of them fleeing war and poverty.