Frans van Dijk of Dutch aid group Terre Des Hommes Netherlands told AFP on the sidelines of a conference in Denpasar that the numbers of children working in the sex tourism trade was on the rise.

“It's difficult to work out the real number but we are sure that the reality is much more” than estimates of 60,000 to 70,000, he said at the three-day Southeast Asia Conference on Child Sex Tourism.

He said victims and their parents were generally reluctant to report abuse due to shame and embarrassment, or were paid to stay quiet.

The situation was especially bad in Asia because some Asian men believed that having sex with children increased longevity, he said.

Indonesian expert Irwanto, of the National Coalition for the Elimination of Commercial Sexual Exploitation of Children, said children were “groomed” for prostitution with financial incentives such as payment of school fees.