A harrowing trial over the alleged gang rape of teenage girls in the high-rise tower blocks of a poor Paris suburb has shocked France, exposed a culture of youth violence and threatens to spark a row over the justice system when verdicts are delivered this week.

Nina and Stephanie – not their real names – said that for years they were too scared to speak out about what they allege were months of almost daily gang rapes when they were 15 and 16, growing up on rundown estates in Fontenay-sous-Bois outside Paris. In 2005, Nina was left unconscious by one final brutal beating following years of abuse and told a female police officer. What followed was a trial that has shaken the country as it struggles to deal with a spate of gang rapes of teenage girls by youths on estates across France.

The alleged Fontenay-sous-Bois attacks took place between 1999 and 2001. Nina, now 29, told the newspaper Libération she had moved to the housing estate aged seven with her mother and brother after a divorce. She was described as good at school and a tomboy. One night returning from the cinema, aged 16 and a virgin, she said, she was grabbed by a local group of youths, taken to basement cellars in the flats, raped and subjected to a series of brutal sex attacks by scores of local boys. The extremely violent, prolonged attacks by large groups of boys continued daily, in car parks, stairwells, apartments, cellars and the empty playground of a local nursery school. She said there would be "at least 25" youths present during attacks in which she screamed, protested, cried and vomited. One witness described 50 boys "queuing" to attack her.

Told that her flat would be burned down if she spoke out, she was afraid to tell her mother, who noticed she was washing eight to 10 times a day.

Nina, who has put on 70kg (150lb) since the attacks, described gaining weight as a "shell" behind which to hide. She allowed herself to be filmed by the media outside the trial hearings to encourage other victims to go to the police, saying: "It was the accused who should hide, not me," and was praised by her lawyers for speaking out in what they said had become a dangerous "culture of silence" on the estates. At the start of the trial, the alleged victims were hailed in the media for their bravery. But the jury trial, held behind closed doors because the accused were minors at the time, has taken place under a tense and heavy atmosphere. One alleged victim, Stephanie, tried to kill herself four days into the hearings. Nina, left infirm by the attacks, was overcome and had to leave court for much of the proceedings.

The 14 men on trial, now aged between 29 and 33, many of whom are married with families and jobs including one ambulance driver, deny rape. Some of them said sex took place but was consensual and that the alleged victims "liked sex". Details from the trial conveyed to the press showed some defendants making comments such as that the women were too ugly to rape, or that sexual relations had not taken place "because if they had I would have heard Nina moaning in pleasure". The women's lawyers complained that some had dismissed the alleged victims as "liars or nymphomaniacs".

Reports by psychiatric experts concurred that the women had been sexually attacked.

In theory, the accused risk a maximum of 20 years in prison, but the state prosecutor this week recommended prison sentences of between five and seven years for eight of them, all minors at the time of the attack. For six others, the prosecutor said there was a "doubt", without elaborating. The women's lawyers said they were shocked by the sentence recommendations. Lawyers on both sides have complained of an incoherent trial.

Verdicts will be delivered tomorrow.