The case is expected to last four months and is being heard in a specially constructed wooden hall in the law courts built to accommodate the 60 lawyers, many of the 45 victims, and the accused, who face sentences ranging up to life imprisonment if convicted.

Sixty lawyers are involved in the trial, and the 430-page prosecution case will take four clerks three days to read out to the three judges and the nine-person jury to be selected.

Proceedings are closed to the public but covered by news reporters, 150 of whom have been accredited. Outside, police blocked the street and bystanders watched with curiosity as the defendants arrived in a number of vans.

Harrowing testimony

The testimony to be heard from the victims, who were aged from six months to 12 years at the time, has been deemed so painful that jury members will have access to a special psychiatric team.

"I expect that first of all the children will be listened to," said Alain Fouquet, one of the lawyers for the victims, outside the courthouse. "They know what happened."

Details of the allegations against the 39 men and 27 women make appalling reading.

All come from the poorest and least educated sections of society, and lived in the Saint-Leonard quarter of Angers, a largely pleasant and leafy historic town.

At least 50 children abused

Investigators were alerted to the network when they decided to keep tabs on Eric Joubert, a former convicted sex offender released in 1999 who was supposed to be undergoing a course of psychiatry. He and another former offender, Franck Vergondy, are alleged to have founded the ring.

According to the prosecution, between 1999 and 2002, nearly 50 children were raped or abused -- though the overall number could be much higher.

The prosecution has gathered evidence said to show that parents bartered their own children for small sums of money, food parcels and cartons of cigarettes. One girl of 10 was allegedly raped by more than 30 adults.

Authorities failed to act?

Most of the abuse took place in Vergondy's apartment, prosecutors say, but also in sheds by garden allotments on the outside of Angers and in caravans. Locals said they were aware of a constant traffic of "voiturettes" -- cheap electric cars that need no licence -- but no one ever made a comment.

For many in France, one of the shocking elements in the case is the number of women involved. Of the 39 accused who are in custody, 13 are women. Most of the accused lived off social welfare, and were thus in regular contact with French government agencies which failed to follow up warning signs of the suspected crimes.

Three of the defendants face life in prison if they are convicted, and the others lesser terms ranging from three to 20 years.