MEXICO CITY - Mexico violated human-rights conventions by failing to investigate properly the murders of three young women slain in 2001 during a now-infamous wave of killings in the border city of Ciudad Juárez, an international tribunal ruled yesterday.

The Inter-American Court of Human Rights ordered the Mexican government to pay hundreds of thousands of dollars in damages to the families of the three victims and directed authorities to take other steps aimed at acknowledging its failings and finding the killers.

The court ordered Mexico to erect a monument commemorating the hundreds of women slain there since 1993 and said Mexican authorities should revise training and investigative guidelines to improve handling of cases involving murdered or missing women.

The binding decision marks the first time an international tribunal has judged Mexico for its handling of the so-called Women's Murders in Juarez.

It largely validates charges by numerous groups that authorities in the state of Chihuahua bungled the investigations or never bothered to probe deeply.

More than 350 women and girls were slain in Juarez - many bearing signs of rape and mutilation - over more than a decade. Most of the killings have not been solved.

Activists called the 156-page decision a blow for justice in a case where many of the dead were impoverished factory workers.

"It represents hope for thousands of people, of mothers, of desperate family members with nowhere to turn for help, no one to bring them justice," said Irma Guadalupe Casas Franco, director of Casa Amiga, a Ciudad Juárez group that works with victims' families.

Lawyers for families of the three victims, ages 15 to 20, said the court-ordered remedies could improve Mexico's mistrusted judiciary.