The application, which has five to 10 million users globally, is most popular in New York and Hong Kong, Wiklund said in an interview with technology website CNET last April.

Skout lets users trade photos, instant messages and virtual gifts. Like other new networking apps - such as Highlight, Circle and About.me - it can check a user's location and connect people who are nearby.

The app was meant for adults, but a teenage version was launched for 13- to 17-year-olds after the company found they were using it anyway. That app has safeguards, including a proprietary technology which Wiklund refers to as 'the creepinator', that checks for nude photos, sexual messages, profanities and other inappropriate activity.

Wiklund said more than a quarter of Skout's staff were dedicated to monitoring and screening the network to keep adults out of the kids' pool. Under its zero-tolerance policy for inappropriate and suspicious behaviour, Skout says it bans 'tens of thousands of devices each month'.

The rape allegations raise larger questions about the safety of social networking apps and sites for young people. Despite their filters sites find it almost impossible to control who goes where.

In Skout's case, a majority of its users sign in through Facebook, which officially forbids members under the age of 13. But Facebook has acknowledged that younger children find ways onto the site. The company said last week that it was fine-tuning controls that would allow children under 13 to join.

In Hong Kong, it is not known how widespread the usage of dating apps are. Several teachers at local and international schools in Hong Kong said they were unaware of their students using Skout or similar apps, but acknowledged it was unlikely that students would confide in them about their dating habits in any case.

Local NGOs Against Child Abuse and the Hong Kong Federation of Youth Groups, said they had not come across cases where teenagers were lured using dating apps and sexually assaulted. 'I've heard of cases where they meet through the internet, chat on MSN and then maybe are sexually abused on a date,' said Wong Wa-kit , the head of the Chuk Yuen centre managed by Against Child Abuse. 'But now mobile phone apps are very popular, so it's a problem for us [to figure out] how to stop this .'

She said that not many people who had been sexually assaulted after being contacted online would come forward, and urged parents to learn about how their children use technology and tell them of the risks.

Skout, which is testing and updating safeguards, said its closure would be temporary. 'We know how much teenagers value Skout, and we apologise for this disruption ... but we hope they will understand that we are acting in the best interests of the community,' said Wiklund.