A police spokesman in Brisbane said that the men, aged between 29 and 64, had been caught with more than two million images of child pornography.

The grandfather is alleged to have recorded sexually explicit images and made films of the child over a period of two years.

Eurojust, the European Union’s coordinator of investigations and prosecutions, told Australian national broadcaster ABC that 40 arrests had been made in Britain, 21 in France, 11 in Spain, eight in Sweden, five in Belgium, four in Italy, two in Iceland and one in Denmark.

“The dismantling of a commercial child pornography enterprise and the removal of 23 children from harm in Europe and a child in Queensland is an outstanding result,” Detective Superintendent Peter Crawford said.

“There is no lower form of human behaviour than those that preside over the commercial sexual exploitation of children.”

Video footage

The international dragnet, codenamed Operation Koala because of its Australian origins, was put in train last year when Queensland police intercepted video footage of the sexual assault on two young girls.

Their Belgian father was tracked down and arrested along with a 42-year-old Italian who filmed the assault. A search of the list of subscribers to his website led to arrests in 28 countries.