An internal report by German police describes how women in the western city of Cologne had to run through mobs of drunken men who attacked them during New Year's celebrations, an experience likened to "running the gauntlet".
The report, details of which were widely published by German media on Thursday, added to witness accounts describing a string of sexual assaults that have sparked a heated debate about migration and the police's failure to prevent the mayhem.
Chancellor Angela Merkel said Germany must examine whether it has done enough to deport foreigners who commit crimes, after police said the perpetrators of the attack were of "Arab or North African origin".
While officials have cautioned against casting suspicion on migrants in general, the attacks have been seized on by some opponents of Germany's welcoming stance toward those fleeing conflict after the country registered nearly 1.1 million asylum-seekers last year.
"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," Ms Merkel said.
She described the New Year's assaults as "repugnant criminal acts that... Germany will not accept", and said changes to the law and increasing police presence may be examined.
"The feeling women had in this case of being at people's mercy, without any protection, is intolerable for me personally as well," she said. "And so it is important for everything that happened there to be put on the table."
German daily Bild on Thursday published extracts from an unidentified senior federal police officer's report on the attacks.
It recounts how federal units, who are also in charge of policing the railway system, were met by "anxious citizens with crying and shocked children" when they arrived at Cologne's main railway station on New Year's Eve.
The officer, said to have been in the job for 29 years, describes how "several thousand male persons with a migrant background" hurled fireworks and bottles into the crowds of revellers who had gathered in front of the city's cathedral to celebrate the new year.
The situation became tenser at 11.45pm (10.45pm GMT) when more people arrived at the train station.
"Unaccompanied and accompanied women had to literally 'run the gauntlet' of very drunk men," the report said.
Officers managed to clear the square, but struggled to cope with the large number of violent men, it said.
"In the course of the operation numerous crying and shocked women/girls approached officers and told them of sexual assaults by male migrants/groups. Unfortunately it wasn't possible to identify them any more."
Federal police declined to comment on the internal report, which was also published by German news agency dpa and the news portal Spiegel Online.
The scale of the attacks has prompted calls for tougher rules on criminal foreigners. Germany's justice minister said asylum-seekers could be deported if they are found to have participated in the assaults.
Justice Minister Heiko Maas said in an interview with the Funke newspaper group that the law already allows for people to be deported during asylum proceedings if they are sentenced to a year or more in prison.
"The courts will have to decide on the level of sentences, but that penalty is in principle absolutely possible for sexual offences," he said.
Police said onThursday they have now received 121 criminal complaints alleging sexual assault and robbery during the New Year's Eve festivities. That includes two accounts of rape.
They said investigators working with video footage have identified 16 young men - largely of North African origin - who may be suspects and are working to determine whether they committed any crimes. Authorities do not yet have names for most of the men.
Interior Minister Thomas de Maiziere said on Wednesday that "anyone who commits serious crimes, whatever status he is in, must reckon with being deported from Germany".
"If it turns out that refugees were the perpetrators, then they forfeited their right to be guests," Andreas Scheuer, the general secretary of the conservative Christian Social Union - the smallest party in Ms Merkel's coalition government - was quoted as telling Bild.
Responding to widespread criticism of the police's handling of the incident, Cologne's police chief Wolfgang Albers said he would report to the regional government on what happened but would not publicly give further details before a meeting Monday of the state legislature's home affairs committee.