One of Portugal's most famous television presenters and a former ambassador were among six men found guilty yesterday of involvement with a paedophile prostitution ring that exploited children from state-run orphanages.

The guilty verdicts handed down to TV presenter Carlos Cruz and the five others exposed the truth of more than three decades of rumours about systematic abuse of young boys at the 230-year-old Casa Pia network of orphanages.

It was only when Joel, a former orphanage boy, came forward in 2002 and accused some of the country's best-known names of being involved that Portugal woke up to full horror of the scandal.

Members of Portugal's media, civil service and professional elite were alleged to be regular abusers of the boys, some younger than 14. Even well-known politicians were involved, it was initially rumoured. A flood of accusations from boys who had passed through the Casa Pia system followed. Some 32 boys alleged at least 800 crimes.

The case pitted the orphanage boys against a group of well-educated, influential people – including a former ambassador to Unesco, a lawyer, a doctor and Cruz. Yesterday, eight years after they dared to speak out, the boys finally won their case.

The four men and two former orphanage employees received sentences of between just under six years and 18 years. Carlos Silvino, a 53-year-old Casa Pia worker who confessed to 600 crimes and gave evidence against other defendants was sentenced to 18 years.

"The court recognised that we were telling the truth," said Bernardo Teixeira, one of the victims. "It's a happy ending for us. The paedophiles are going to jail."

The court ruling was hailed as a victory by those fighting for children's rights in Portugal. "The stories that I heard were the most terrible of my life," said Catalina Pestana, who was put in charge of the Casa Pia orphanages after the crimes were first reported in 2002.

"I think Portugal, the country, all of us, won a lot from this process. Now, when a child accuses an adult, nobody will look with the same lack of attention that they did for many years."

The court case lasted six years, bringing additional outrage about the slow way in which Portugal's legal system worked. The case was already in court when three-year-old Madeleine McCann disappeared while on holiday with her family in the Algarve in 2007. Portuguese police were, at the time, defensive about claims, particularly those made in the British press, that they had a history of mishandling cases involving children.

Buried in the case paperwork are allegations that Casa Pia was known to paedophiles internationally and that some flew in to abuse children from the orphanage, according to at least one source familiar with the case.

Portuguese media provided live running coverage of the reading of the sentence. The judges said they were giving only an abbreviated version of events, with a much fuller judgment due to be made public next week. The senior member of the three-judge panel, Ana Peres, began by warning those present that the abuse they described would be graphic and shocking. "Some of the accounts could be considered pornographic," she said.

Cruz, 68, who was once voted Portugal's most popular man, had paid for sex with a 14-year-old, the judges declared. He also abused at least one other boy. The father of two was known as "Mr Television" after several decades as a national star. He was sentenced to seven years in jail.

A doctor, Ferreira Diniz, was also sentenced to seven years and a former ambassador, Jorge Ritto, 74, to six years, and the former Casa Pia ombudsman, Manuel Abrantes, to five. They were found guilty of abusing several young boys.

The court found that boys had been regularly taken to a house in the eastern town of Elvas during the 1990s to meet the paedophile clients. Abuse had also taken place in Lisbon.

Some of the victims who gave evidence were present to hear the verdicts. Psychiatrists said several of the victims had tried to kill themselves after denouncing the abuse to the police. One threw himself from a second-floor window.

Lawyers said their clients would almost certainly appeal. "It seems inevitable that we will have to appeal," said Cruz's lawyer, Antonio Serra Lopes, before the sentence was read out. "This is the first round."

• This article was amended on 7 September 2010. The original headline said Carlos Cruz jailed for seven years. This has been corrected.