Italian police have raided the homes of 15 young men and three boys who are suspected of involvement in a series of sexual assaults during New Year’s Eve celebrations in Milan. Nine women have so far reported that they were assaulted during celebrations in front of Milan’s Cathedral on Piazza del Duomo. The case has prompted comparisons with the mass sexual attacks and muggings that took place in the German city of Cologne on New Year’s Eve in 2015-16. Police said the 18 suspects are aged between 15 and 21 and are foreign or Italian of north African origin. Raids were carried out early on Tuesday morning at homes in Milan and Turin. Several women, including two Germans who had been visiting Milan, came forward with their reports in the days after New Year’s Eve, with the number rising to nine as of Tuesday. Police believe more women were assaulted. Police identified the suspects based on CCTV images, the accounts of the victims and witnesses, as well as via the analysis of social media posts. The women shared similar stories of being dragged into the crowd, shoved and groped during the fireworks display. A 19-year-old woman alleged that she was set upon by a gang of youths at about 1.30am and attacked for about a minute before help arrived. Her friend managed to get away. The two German women said they were pushed up against barriers and sexually assaulted. They filed their reports after returning to Germany. One claimed the police didn’t respond to cries for help. In a video, the women can be seen trying to escape. “I realised they were touching me and we wanted to escape but there were too many of them,” one of the German women told the Italian news agency Ansa. “I hope they find them and that justice is done for us and all of the other girls that were molested that night.” One young woman suffered scrapes when her jumper was torn and trousers pulled down. She was taken to hospital by police for examination. Another was attacked on a street close to the square. The Italian interior minister, Luciana Lamorgese, last week said that no effort should be spared in ensuring that such “deplorable behaviours” never happen again. However, the incidents have sparked a political debate, with rightwing parties calling for the city’s councillor for security, Marco Granelli, to be dismissed over the management of the New Year’s Eve celebrations. “The leftwing goodness, even in the face of the evidence, is really disgusting,” said Alessandro De Chirico, a councillor at Milan’s town hall from the Forza Italia party. The city’s leftwing mayor, Giuseppe Sala, condemned the “very serious attacks” that have besmirched the city. The case has drawn comparisons with the Cologne incident, when up to 1,000 young men, many of north African origin, carried out a series of sexual assaults, rapes and muggings close to the city’s cathedral. Cologne’s police were also accused of failing to respond to the attacks while a fierce debate erupted amid accusations of a police and media cover-up over fears of whipping up anti-foreigner sentiment in the wake of the migrant crisis in 2015. More than 1,200 women were attacked, 24 of whom said they were raped. The attacks were condemned by the then chancellor, Angela Merkel, as “abominable”.