Indonesian pop singer Nazril Irham faces questioning by police after homemade explicit videos of him were circulated on the internet.
The 28-year-old could face 12 years in jail for breaking anti-pornography laws with the films, which feature him and two female companions.
One of the women, who is married, could face a prison term for adultery.
The president of the predominantly Muslim country says the case shows that internet controls should be tougher.
"We have increasingly realised that our nation should not stay naked and be crushed by the information technology frenzy, because there will be many victims," said Susilo Bambang Yudhoyono.
Irham, widely known by his nickname Ariel, voluntarily went to the police after being named a suspect in the case, dubbed the "Peterporn" scandal after his band Peterpan.
The authorities said they were prepared to arrest him.
The two women, TV presenters Luna Maya and Cut Tari, have seen their careers suffer since the tapes first emerged in early June.
Maya is the singer's current girlfriend, while Tari used to be linked to him. The two women were filmed on separate occasions.
All three celebrities have denied uploading the material to the internet, but still could face stiff penalties for breaching anti-pornography laws.
The Indonesian government is intent on tightening internet controls to filter out negative content, while pirated DVDs sold on the streets are a main source of porn in the south-east Asian country.
It is the first celebrity sex tape scandal to hit Indonesia.