A leaked document from one officer claims there were "anxious citizens with crying children" as women were robbed and assaulted.
An internal police report following a string of sex attacks during New Year celebrations in Cologne has described how women were forced to run through mobs of drunken men.
The document, made public by German newspapers, came amid allegations that officers struggled to cope with the large crowds of disorderly revellers - as "several thousand males with a migrant background" hurled fireworks and bottles.
It recounted how policemen were met by "anxious citizens with crying and shocked children" as numbers swelled at Cologne's main train station in the minutes before midnight.
Jens Floeren, a federal police spokesman, has confirmed the authenticity of the report - but stressed it was the "subjective assessment" of one officer who was at the scene.
In total, 121 criminal complaints of sexual assault and robbery during the 31 December festivities in the city centre have been filed, including two accounts of rape.
Investigators have identified 16 young men, largely of North African origin, who could be suspects - and earlier in the week, interior minister Thomas de Maiziere warned that any asylum seekers who committed a serious crime "must reckon with being deported from Germany".
Meanwhile, Chancellor Angela Merkel has called for a "fundamental" debate on how to integrate the 1.1 million refugees who were registered in the country last year, and described the assaults as "repugnant criminal acts that Germany will not accept".
She added: "The feeling women had in this case of being at people's mercy, without any protection, is intolerable for me personally as well.
"We must examine again and again whether we have already done what is necessary in terms of deportations from Germany in order to send clear signals to those who are not prepared to abide by our legal order."
Cologne's police chief has said he will respond to widespread criticism of how his force handled the incident when he appears in front of the state legislature's home affairs committee on Monday.
In Switzerland, local police have said several women were also robbed and sexually assaulted in Zurich on New Year's Eve in attacks which seemed "a little bit similar" to those reported in Cologne.
Officers in Finland have also confirmed that there were a higher-than-average number of sexual harassment complaints in Helsinki as revellers welcomed in 2016, with officials claiming they were tipped off about groups of asylum seekers who were planning to assault women.
Members of Cologne's Muslim community, including some who have lived in the city for decades, have joined other Germans in condemning the attacks.
One woman said: "Everywhere it says this has something to do with Muslims. What I read and learned in the Koran is completely different.
"I've been here for 30 years myself and I've never seen anything like this."
A German-Tunisian lawyer has described the assaults as inexcusable, but criticised the police for identifying some of the attackers as North African before making any arrests.
Mehdi Labidi said: "Germany is a tolerant country but I find this really strange that an entire ethnic group is being branded as criminals.
"If far-right extremists attack North Africans then we are going to file a criminal complaint against police for incitement."
