Photographs of unnamed senior government officials with young boys from Lisbon's Casa Pia orphanage were among the evidence reportedly available to police after they arrested a former orphanage employee called Carlos Silvino.

A number of former residents, and the mother of one boy who is still there, have denounced sexual attacks on children at what is known as Lisbon's most famous orphanage.

Mr Silvino, it was claimed, abused children himself and procured boys for a powerful group of clients.

He has publicly denied the allegations and was expected to repeat that denial at a closed-door bail hearing in Lisbon yesterday.

What has most shocked the Portuguese have been the revelations that systematic sexual abuse of children at the home had allegedly been going on for more than 20 years and had been known to police and other authorities for most of that time.

A former president, General Ramalho Eanes, was allegedly among those who knew about abuse at the home but failed to stop it.

The identity of the mysterious group of powerful paedophiles remained a secret yesterday, with only one person prepared to admit she knew at least some of the names.

Former secretary of state for families, Teresa Costa Macedo, said she had sent a dossier containing photographs and testimonies from children to the police 20 years ago but they had done nothing about it, while she was subjected to a campaign of threats.

"He [Silvino] was just one element in a huge paedophile network that involved important people in our country," Mrs Costa Macedo explained in a newspaper interview. "It wasn't just him. He was a procurer of children for well-known people who range from diplomats and politicians to people linked to the media."

The material sent to the police, which yesterday appeared to have been lost, was damning proof of the activities of the paedophile ring, Mrs Costa Macedo said.

"There are photographs, an account of the methods used to spirit children out of the orphanage and testimonies of a number of children," she explained.

Mrs Costa Macedo said that many of the photographs were found at the house of a Portuguese diplomat in the town of Estoril, 20 miles from Lisbon. Four children who had gone missing from the orphanage were discovered at the house, where they had spent several days allegedly under lock and key.

President Eanes was introduced to five boys who told him of the abuse occurring at the orphanage in 1980 but failed to act on it, according to Mrs Costa Macedo.

There was no suggestion that General Eanes, a popular and respected figure who did not comment on the allegations yesterday, was involved in the paedophile ring.

Portuguese police insisted yesterday they had no record of the documents sent to them by Mrs Costa Macedo.

She said she had been the target of a campaign of intimidation to make her stop investigating the case.

"I received anonymous threats, by phone and post. They said they would kill me, flay me and a lot of other things," she said.

That campaign had started again yesterday, she said, with threatening phone calls made to her home.

Portugal has increasingly been under the scrutiny of anti-paedophile groups who have denounced its lax laws and uninterested courts for creating a paedophiles' paradise in Europe.

Belgian and Dutch paedophile groups are reported to have operated in Portugal, with foreigners travelling to the island of Madeira to seek out young children.

Investigators from the Swiss-based Innocence in Danger group, which claims children regularly disappear from the poorer streets of Portuguese towns and cities, say they too have been harassed and threatened.

Mr Silvino claimed his accusers were making up their allegations. "It is all lies," he said.

The orphanage's director and deputy director were sacked on Monday as the government pledged to clear up the case as soon as possible.