Twelve people were arrested in Germany and three men from Vienna and the provinces of Carinthia and Vorarlberg who took obscene photographs and films of children aged between eight and 12 and posted the material via an internet forum, police said at a news conference in the Austrian capital.

The children were from the men’s own families, the police said.

A 41-year-old butcher from Vienna was the “star of the forum,” investigator Harald Gremel said, boasting to fellow users exactly what he intended to do with his 10-year-old stepdaughter that evening, then filming the abuse and posting the pictures on the internet.

The man, who had three children of his own, had a preference for young girls aged between two and 11, Gremel said. His wife claimed not to have been aware of the abuse, even if she said she found it strange that he sometimes locked himself in a room with her daughter.

In a joint operation with German police, investigators were able to identify 136 members of the network and carried out a total 178 house searches in a number of different countries.

The suspects from Carinthia and Vorarlberg, aged 22 and 36 respectively, are accused of abusing the 12-year-old son of a friend and the eight-year-old daughter of one of their partners. They did not actually post any pictures of the abuse on the forum, but described it in detail.

Police in the western German city of Wiesbaden made nine arrests. The investigation was originally launched in Germany in January with the Austrian police becoming involved in May.

Among the suspects are Austrian, German, Swiss, Spanish, Bulgarian, Canadian and US citizens.