Three former members of the banned paedophile association Martijn will be prosecuted for continuing to propagate sex with children and sharing tips on sexual abuse, the public prosecution office has confirmed to broadcaster NOS.

The Dutch supreme court ruled in 2014 that the organisation should be banned because the protection of children should weigh more heavily than freedom of expression, ending a protracted legal battle.

RTL journalists discovered that Marthijn U, Neslon M and Norbert de J had been active on social media and were part of a closed email group for former members of Martijn. After infiltrating in the group for months they discovered tips on child abuse were being shared there.

Paedophilia (having fantasies about sex with children under 13) is considered a sexual preference and is not against the law but the sexual abuse of children can carry heavy penalties.

On publication of their findings, lawyer Yme Drost filed a report with police on behalf of the child protection organisation Strijd tegen Misbruik against the three men.

According to figures from the national monitor on child sex abuse almost half of girls and one in five boys are confronted with a form of sexual violence punishable by law.