The Catholic church in Chile is under investigation over allegations that priests played a central role in a network that stole newborn babies from single mothers.

Police investigators are now probing dozens of cases in which unmarried women who became pregnant were pressured by priests to give up their child for adoption. Those who refused were anaesthetised during delivery and, upon awakening, told that the child had died. The healthy babies were hidden from their biological mothers and given away in order to be raised by married couples in "traditional" Catholic families.

Church leaders now admit they have known about the network for at least 10 years. Unlike in Spain and Argentina, where babies were stolen from families considered to be too poor or too subversive to raise the children well, the motivation in Chile was to shield the reputations of well-off families from the social stigma of unmarried motherhood.

Most of the cases now being investigated date from the 1970s and 1980s, but some were reported in 2005.

Chile's child protection agency – Sername – has now opened an investigation and is working with detectives to determine how many children are involved.

Documents from the Sername investigation describe how parents were tricked into believing that their baby had died.

Matias Troncoso, 33, a well-known Chilean photographer, was one such baby. Troncoso always knew he was adopted, but when he began asking questions about his biological mother, the answers did not add up. His birth was not registered until he was six years old, and the clinic where he was born refused to release his records.

The doctor who delivered him was losing his memory, but enough details leaked out that Troncoso began to suspect a plot.

Last month his suspicions were confirmed when Chilean investigative news site Ciper reported the allegations. In a series of online articles, the collective's reporters tracked down and documented an underground network of wealthy families, gynaecologists, social workers, lawyers and, at the heart of the scheme, Gerardo Joannon, a gregarious and popular priest.

Troncoso, who ended up as the single son of a loving, upper-class family, had nothing but praise for his adoptive parents and said they never hid the fact that he was adopted. But he was extremely critical of the role played by the church. "They had funerals with empty caskets," he said.

Father Joannon has admitted working with 10 doctors who helped coordinate the adoptions. "A young single woman who had a baby was looked at very badly," he said when confronted by Ciper reporters in March. "I wouldn't say it scrubbed out their life, but it was something close to that. Nobody wanted to marry them."

Joannon insists his role was limited. He told Ciper: "The only thing I did was put [the pregnant young women] in contact with a doctor who made the effort to find families that were desiring to have a child."

Interviewed by a Chilean TV crew, Joannon declared, "I am not going to help [the investigation] with anything, I have nothing left to say." Church officials then announced that Joannon has been ordered to refrain from speaking further about the cases, which investigators now believe involves six Santiago-area hospitals.

Father Joannon insists he only participated in underground adoptions in which the biological mother agreed to "donate" the baby to a second family. But at least one mother has said he pressured her to give up her child, and alleges that when she refused, he participated in the disappearance of her newborn daughter. A second mother described Joannon stalking the maternity ward, pressuring her to hand over her newborn.

Several other priests are alleged to have been involved in the scheme, but have not been named.

Catholic leaders in Chile have distanced themselves from Joannon. His weekly mass was suspended in April and Alex Vigueras, a spokesman for the church said it was clear that the babies were taken without consent. "What I find most troubling is to have said that the children died, knowing that it was not the case."

Vigueras said that Joannon and the baby-snatching ring had "committed an injustice … various rights have been violated." In a communiqué from the church, Vigueras promised to collaborate with investigations by Chilean law enforcement agencies.

A website set up by victims has logged dozens of alleged cases. Some of the inquiries come from parents looking for their children and others from children looking for their parents.

"Joannon made the contacts but he is just one lead on this problem," said Arturo Fellay, whose wife is searching for her biological parents. "There are many other cases of boys and girls who were said to be dead and were taken away or given or sold to families under a secret that was kept for years."

Asked about the ethics and honesty of holding funeral services for newborn children who in fact were alive, Joannon told reporters from Ciper, "I never held a funeral mass … these were masses where thanks were given to God for that day in which the young woman made such a tremendous sacrifice."

Pressed with evidence by parents that funeral services were indeed held, Joannon then said he was "sure that [the baby] was dead. The doctor told me [the baby] was dead."

Troncoso, the photographer who is now searching for his biological mother wants answers. "I don't know my birthday. I don't know my [biological] mother" he said. "These woman entered the clinic. They were put to sleep and when they woke up were told 'Your baby has died.' Basically it was kidnapping."

Troncoso says he is not interested in filing criminal charges. "Justice is not just the whip of vengeance," he said. "It's essentially about truth. How can you take a baby from a mother and convince yourself that you are doing a good deed?"