A computer forensic expert is warning that an underground group of teens bent on causing mayhem may be behind hoax bomb threats causing havoc in New Zealand schools this week.

Special Tactics managing director Daniel Ayers is warning authorities to brace for more bogus bomb scares as a group operating on the dark web, known as "evacuators", target schools to bring about as much chaos as possible.

Mr Ayers said the group was spreading its reach internationally through an online appeal for teenagers to nominate their schools for "swatting", a term used for making a false complaint that leads to high-level police response.

Last month, the group posted a note on the anonymous website Pastebin that it was accepting $5 to $20 Bitcoin payments to call in bomb threats at schools, businesses and sport grounds.


"Until March, 2015, you may send in requests for your school/work/business/etc to be sent a bomb threat. After March 1st, of 2015, we will be accepting Bitcoin only as payment," the group wrote.

The fees range from $5 for schools through to $50 for major sports events.

This week, there were at least 33 primary, secondary and intermediate schools forced into lockdown after malicious calls were made to principals threatening live bombs in schoolyards across the country.

One call targeted Napier's Tamatea High School.

In each case, the call appears to have been made locally using voice over internet technology (VoIP) that converts international calls into local phone calls.

Mr Ayers said it was important for the loophole to be closed at a government level.

"What's going on at the moment is so harmful to society that there needs to be a regulatory response to it to either make it impossible to make voice-over-IP calls out of or into New Zealand, or at least strengthen the protection so if they do things they shouldn't they can be stopped."

He said the sudden explosion of hoax threats could have been requested from local school children or simply the group spreading its reach from across the Tasman, where it had caused a headache for authorities in recent weeks.

"What we don't know is whether it's spreading because this group is bored and they just want to find more targets or it's spreading because kids at various places, particularly schools, are contacting the group and inviting them to do it to their school because they think it would be fun to get them out of class."