Allegations that a child sex ring has been operating out of state-run children's homes in Portugal for decades has prompted intervention by President Jorge Sampaio.
President spoke of national shame
He has said he will do everything in his power to ensure a full investigation is carried out.
"The impunity which for decades on end has made this case a shame for all of us will finally end," President Sampaio said.
The scandal emerged last November but escalated last week with the arrests of the spokesman of the main opposition Socialist party and of a former Portuguese ambassador to South Africa.
The impunity which for decades on end has made this case a shame for all of us will finally end
The developments sparked an outcry in Portugal, particularly when it was reported that a former president and several government ministers, as well as the police, knew of the allegations as far back as the early 1980s but failed to take action.
"Faced with the horror that so many children, who were entrusted to us to be educated and cared for, were victimised it is necessary to declare here that the president is certain that the guilty will be severely punished," President Sampaio said in a speech.
The latest high-profile arrests are of men publicly accused of sex abuse by former children of Casa Pia, Portugal's largest network of homes for troubled children.
Casa Pia first made the headlines following allegations that an employee at the institution allegedly helped wealthy child molesters to meet young boys in his care for over two decades.
The employee, a driver at the institution, was arrested and is in custody awaiting trial.
Since then a popular game show host, a well-known doctor, a lawyer and a former director of Casa Pia have also been arrested and are also in custody pending trial.
Police are due to question the television personality on Friday amid widespread media speculation that more arrests of prominent people are imminent.
Staff at the network of 10 children's homes, which currently has 4,600 children in its care, have said they believe more than 100 boys and girls currently with them may have been sexually abused.
Many of those suspected of having been victimised by staff at the 200-year-old institution are deaf-mutes.