German Chancellor Angela Merkel came under mounting pressure yesterday for her welcoming stance toward migrants, which opponents have linked to a shocking rash of apparently coordinated sex attacks in Cologne on New Year's Eve.

Police in the western city told AFP they have received more than 100 complaints by women reporting assaults ranging from groping to at least one reported rape, allegedly committed in a large crowd of revellers during year-end festivities outside the city's main train station and its famed Gothic cathedral.

Victims blamed men of "Arab or North African" appearance, enflaming a heated public debate about Germany's ability to cope with the nearly 1.1 million asylum seekers the country took in 2015. Authorities have said there is no concrete indication that the perpetrators were asylum seekers.

However critics of Merkel's liberal refugee policy charged that the Cologne assaults proved she was playing with fire without a clear plans.

Late Tuesday 200-300 people gathered in front of Cologne cathedral calling for more respect for women. One female demonstrator held a sign reading: "Mrs. Merkel, what are you doing? This is scary".