An online platform said to be one of the largest websites for child sexual abuse images in the world has been closed down by German police after a lengthy investigation. The Boystown platform, which had a membership of more than 400,000 international subscribers and was active for almost two years, was accessible only via the darknet, a component of the wider internet for which special software is needed. It was used for the swapping and sharing of images and films, mainly of boys, according to investigators from Germany’s federal investigative police force (BKA). Four German men including the site’s administrators have been arrested and police also raided seven properties linked to the site in North Rhine-Westphalia, Bavaria and Hamburg. In addition to the visual content, which the BKA said contained content depicting the most extreme sexual abuse of small children, there were also two chatrooms on which users could communicate. The arrested men, who have been held in police custody in Frankfurt since mid-April, are a 40-year-old from the area of Paderborn in western Germany, a 49-year-old from Munich and a 54-year-old German resident in Paraguay. The men are believed to have been involved in the administrative and technical aspects of running the site, as well as establishing and maintaining the server, and a subscription service. They allegedly offered users of the platform extensive advice on how to avoid police detection when surfing on the platform. A fourth man arrested, a 64-year-old from Hamburg, is believed to have been one of the most active members of the site, posting more than 3,500 times. The man living in Paraguay, in the Concepción region, who was arrested after German police issued an international arrest warrant for him, is facing imminent extradition to Germany. The arrests followed an investigation initiated by German authorities, as part of a taskforce under the coordination of Europol, in which investigators in the Netherlands, Sweden, Australia, the US and Canada were also involved. Eva Kühne-Hörmann, the justice minister for the state of Hesse where three of the men are in custody, called the police work a “fantastic investigative success story in the fight against the sexualised violence of children and young people”. She said it sent the clear message to those dealing with child abuse images that “the oxygen for people who participate in the spreading of photos and videos is getting increasingly thin”. In the UK, the NSPCC offers support to children on 0800 1111, and adults concerned about a child on 0808 800 5000. The National Association for People Abused in Childhood (Napac) offers support for adult survivors on 0808 801 0331. In the US, call or text the Childhelp abuse hotline on 800-422-4453. In Australia, children, young adults, parents and teachers can contact the Kids Helpline on 1800 55 1800, or Bravehearts on 1800 272 831, and adult survivors can contact Blue Knot Foundation on 1300 657 380. Other sources of help can be found at Child Helplines International